Claude Haiku 5.5

I'm building a snake game where the snake is a train: a locomotive pulling colorful wagons and collecting passengers from the platform. It has to be one self-contained HTML file with all CSS and JS inline and no external resources. The response should be a single fenced html block with nothing else around it, no localStorage, and it needs to look right at 1280×800 and still work down to 375px wide.

I'm checking the remaining requirements: the game has to fit a 1280×800 view and still work at 375px, the start message needs to be visible, and the console must stay clean. Next I'm working out how passengers fit into the train mechanics.

I'm sketching how the train's mechanics would work: stations as grid platforms with waiting passengers, boarding them as colorful wagons, and keeping the track layout manageable. Self-collision ends the run, and I'm still weighing whether crossing the boundary should wrap or crash.

I'm working through how passengers would fit the train mechanics: they wait on platform tiles, and the train picks them up by driving through, adding wagons and points, with the platform repopulating elsewhere after a short delay.

I'm weighing whether passengers should be a simple pickup that grows the train, or something with destinations to deliver. Passengers wait on grey platform cells, and driving the locomotive onto one boards them, adding a wagon and points.

I'm weighing whether the passengers should sit on the platform as a strip beside the track, where the train picks them up as its head comes alongside, but that would make collisions harder to keep clear. Passing straight through a platform tile is simpler, so I'm leaning toward that for now.

I'm picturing the scene as a top-down model railway, with grass, small trees, and a town around the track. I'm still weighing whether the track should be the grid itself, with the train leaving rails behind it, but that would make the path harder to read. For now I'll keep the usual snake rule where hitting its own body ends the run.

I'm settling the visual look now: grassy ground with a track bed, trees around the edge, and grey platforms with yellow safety lines. The passengers will be small figures standing on those platforms that bob a little, with the grid sized around 24×18 cells and scaled to fit the canvas.

I'm picturing the passengers as little figures in coloured shirts that bob on the platform tiles, and the locomotive as a red-and-black steam engine with a puffing chimney and animated wheels. The wagons will be rounded boxes in different colours, joined by small couplers, with passenger heads showing in the windows once they've boarded.

I'm settling on a simple rule where each pickup adds one wagon, with the passenger's shirt color becoming that wagon's color. I'm considering bundled passengers on platforms for bonuses, but that feels like more than the design needs, so I'll keep it simple and polished. I'll track the passenger count, score, and session-only best score in memory instead of localStorage.

I'm thinking about adding a timer to the waiting passengers, so they leave if the train doesn't reach them in time, which gives the player a reason to head for specific platforms. I'm also considering a demo mode where an AI steers the train toward the nearest passenger with a search that avoids collisions.

I'm settling the demo behaviour: an AI steers toward the nearest passenger by search, avoiding walls and its own body, and if no path exists it picks the move that keeps the most room. Before the user starts, that AI plays behind a "Click or press a key to start" message, and once the user clicks or presses a key the train switches to player control.

I'm settling the game states now: a demo state where the AI plays behind a "Click or press a key to start" card, a playing state under player control, and a game over state that offers a restart on the next key press.

I'm settling on the overlay: it will show "Click or press a key to start" with a subtitle about the controls, kept semi-transparent so the AI demo stays visible behind it. The key-press handling needs to start the game and set the direction, and the message has to be on screen at first paint.

I'm weighing a touch option: swipe to steer on the canvas, with perhaps a small on-screen d-pad that appears only on touch screens under 600px wide, though swipe alone might be enough.

Next I'm settling how the board scales: a fixed logical grid of about 30×20 cells, drawn to a canvas that resizes with its container, with devicePixelRatio handled for sharp rendering. I'm also deciding on a simple d-pad for narrow screens, making sure it won't cause horizontal scrolling.

I'm weighing grid sizes now: 30 columns would leave the figures tiny on a 375px screen, so I'm leaning toward 24×16 cells, which gives roughly 37px cells on a 900px board and still about 15px on mobile.

I'm settling the page layout now: a header with the game title, the board on the left, and a side card on the right with the stats and a short how-to-play list. On narrow screens that card will drop below the board instead.

I'm settling on a fixed grid of 24 by 16 cells, with the canvas sized to the largest 3:2 box that fits its container. The overall layout should fit a 1280×800 window without scrolling, so the board stays around 900 by 600 pixels beside a narrow side panel.

I'm weighing whether a fixed 24×16 grid is too coarse for a snake game, since a train could quickly grow long enough to fill the map, though passengers and the body should still leave room for a casual run.

I'm weighing how the train should interact with the platforms: since trains run on track rather than on platforms, the platforms would sit beside the rails, with passengers waiting on them. The open question is whether a train should stop at a station, or simply pass through a platform cell.

I'm weighing whether passengers should sit on platform cells that the train's head has to reach, or whether a train passing alongside a platform should be enough to pick them up. Making the pickup depend on the head reaching a free track cell next to a passenger would be more interesting to watch, but it also makes the AI's pathing harder to get right.

I'm deciding whether the platforms are walkable, so the train can roll right over a station tile to collect passengers. That keeps the mechanic simple, and I'm weighing how to draw the station track through the platform so it still reads clearly.

I'm picturing the board as a yard with grass, trees and rocks as obstacles, and stations with platforms and signs, the train drawn over it all. I'm leaning toward the simpler option, with the train simply rolling over the ground and not drawing track under its path.

I'm thinking about the obstacles now: rocks, trees, or houses scattered across the map that end the run if the train hits them, which the AI will have to route around with its search. For the platforms, I'm picturing a few static grey strips, each about three cells long, placed toward the edges, with passengers waiting on whichever of their cells are free.

I'm settling how passengers and scoring work: passengers appear on free platform cells, a few at a time, each with its own colour and a limited wait. When the head reaches a waiting passenger, they board and the new wagon takes that colour, and I'm weighing whether to add a combo multiplier or keep the scoring simple.

I'm working out how the passengers score: each one who boards adds to the count, and I'm leaning toward a plain 10 points per passenger rather than a combo bonus. Every five passengers the train speeds up a little and a "Level N" toast appears. I'm also weighing whether a passenger who waits too long should leave with a small puff and no penalty, or add a missed counter, and I'm leaning toward keeping it simple with no penalty.

I'm settling whether the edges should kill the train, and I'm leaning toward walls that derail it on contact, since a plain box is the easiest rule to read. Wrap-around tunnels were an option, but they could confuse players, so I'm weighing whether the wall rule is still the simpler choice.

I'm deciding whether the edges should wrap as tunnels or act as walls. Wrapping would make the AI's survival easier and the board more forgiving, but a plain wall that derails the train is the more canonical rule, so I'm leaning toward keeping walls and drawing a fence around the board. I'm also considering a whistle sound and chimney smoke puffs to add some charm.

I'm planning to add synthesized sound (a train whistle and a ding when a passenger boards), but only after a user gesture so the AudioContext isn't blocked. I'll wrap the audio code in a try/catch and include a mute toggle, so it can't break the game.

I'm working out the AI's targeting next: each step it picks the nearest waiting passenger as its goal, and I'm still weighing how to route the train there without running into obstacles or its own wagons.

I'm working out how the AI picks its route: each step it runs a BFS from the head to find the nearest waiting passenger, then plans a path to it that treats the body as blocked, apart from the last segment that will vacate. I'm also planning a safety check on the chosen first move, so the head can't walk itself into a trap.

I'm settling the AI's move choice: for each non-reversing direction that isn't blocked, I'll score it by how much open space a flood fill finds from the new head, with the body shifted to account for the move. Blocked cells include obstacles and body segments, and I'm treating the tail as blocked too to keep the check conservative.

I'm weighing a score for each candidate move: how much open space a flood fill finds from the new head, with obstacles and body cells blocked, and how close that move brings the head to the nearest waiting passenger. The area check guards against trapping, with a heavy penalty when the reachable space is smaller than the train's length.

I'm looking at the AI's move choice in more detail now: it'll flood-fill the open space from each candidate cell and weigh that against how close the move brings the head to a waiting passenger. I'm also planning to add a short grace period before the demo restarts after a crash, so the page keeps looking alive.

I'm planning the drawing layer now: the background ground, grass, and any static obstacles and platforms get pre-rendered to an offscreen canvas once per game or resize, so the frame loop stays cheap. I'm also thinking about the platforms' look, with yellow tactile edges and a small station sign, and where three of them should sit on the map.

I'm settling how the obstacles and platforms get placed: I'll scatter trees, rocks, and houses at roughly 8% density, keep them clear of the start area and the platform cells, and then check that the map stays mostly connected.

I'm working out how the map gets generated: I'll check that the open cells remain mostly connected from the start, and regenerate if they don't. I'm also picking the obstacle types, with trees, rocks, and small houses, and thinking about how the passengers will look, with varied shirts, skin tones, and the odd hat.

I'm settling the passenger spawn rate: a new waiting passenger appears every few seconds on a free platform cell, and I'm leaning toward a cap of three at first, rising to five as the game goes on. Each one has a limited wait, and I'm weighing how fast the train should move, starting around 110ms per step and easing down to a minimum as levels climb.

I'm thinking about how the train's wagons should look: passenger carriages in varied colors, each with a row of windows where the boarded passengers' heads show, and maybe a striped roof. The locomotive will be a steam engine with a dark body.

Next I'm describing how the wagons get drawn: each one is an inset rounded rectangle in its cell, linked to the next by a dark coupler bar between their centers. The wheels and the locomotive's animated spokes and headlight come after that.

I'm working out how each wagon gets oriented along the track: rotating it to face its direction of travel, with the locomotive turned to match its heading. Corners are the awkward part, since a rotated rounded rectangle can look odd there, so I'm weighing whether unrotated square cars would read better as a toy train or whether rotation is still the more convincing choice.

I'm settling how the wagons look from above: rounded rectangles filling most of each cell, linked by thin dark coupler bars between their centers, so the chain reads as continuous. I'm weighing whether to show wheels at the corners or along the sides, and what a roof with a stripe and vents would add when seen top-down.

I'm settling on a stylized toy look for the wagons: a rounded body with a darker bottom edge for shadow and a lighter top highlight, a row of windows along the side, and small colored heads peeking out of the windows when passengers are aboard.

I'm settling how each wagon is drawn when it turns a corner: the windows and body stripes need to line up with the travel direction, so I'm weighing whether to rotate the whole wagon to match its heading, and how that holds up where the path bends.

I'm working out which way each segment faces so the wagons line up with the track. The head's heading is simple, but for the body I'm deciding whether to use the direction toward the head, since the corners make the neighboring directions disagree.

I'm working out how to tell each wagon which way it faces: for the body segments I'm defining the forward direction as the vector from that segment toward the one ahead of it, with the head using its current heading and the tail handled as a special case since it has no segment behind it.

I'm settling on not rotating the wagons: each one will be a rounded rectangle filling about 84% of its cell, with a couple of round portholes for windows, since rotation would only matter for window placement and the corners would look awkward anyway.

I'm weighing whether to draw the wagons' windows as fixed squares near the center of each block, rather than rotating anything, since top-down the sides are what would show windows and wheels.

I'm weighing whether to rotate the wagons along their direction of travel, since elongated rounded rectangles would line up into a continuous train on straight track and only look odd at corners.

Still deciding how each wagon is oriented: I'm leaning toward a rounded rectangle stretched along its direction of travel, with the forward axis pointing toward the locomotive, and I'm weighing how that orientation holds up at corners.

I'm weighing whether to rotate each wagon along its direction of travel, which would make a straight run read as a continuous train. At corners the rotated shape would only link to its neighbor from the side, which seems acceptable, so I'm leaning toward rotation for the more train-like look.

Now I'm settling the wagon look: a rounded body with a darker skirt along the bottom edge, a lighter roof stripe, and wheel bogies on both long sides. Windows sit along the middle, with passenger heads poking out of them when aboard. The locomotive will follow the same approach but be larger, with a cab at the front.

Next I'm settling the locomotive's details: a cab at the rear, a chimney and cowcatcher at the front, a lit headlamp, and spinning wheel spokes driven by distance traveled. Smoke puffs will rise from the chimney and fade. For the platform, I'm picturing simple passenger figures with bobbing motion and a suitcase beside them, and I'm still deciding whether to use an emoji speech bubble or skip it.

I'm adding a timer ring above each waiting passenger that shifts from green to yellow to red as time runs down, with a "!" when it gets low. I'm also thinking about a subtle pulse under waiting passengers so they stand out, plus floating "+1 passenger" or "+10" text and some dust on crashes with a small screen shake.

I'm planning the HUD now: a right-side panel showing score, passengers aboard, level, best score and how many passengers are waiting, plus a short legend on pickups and crashes and a line of controls. I'm also considering a small pill that shows whether the AI is driving or the player is.

Next I'm laying out the overlays: a centered card on the board that says "Snake Express" and asks for a click or keypress to start on first load, and a "Derailed!" card with the passenger count and a play-again prompt on game over. On narrow screens I'm stacking the header, board, and a four-card stats row in a single column, with a touch d-pad that shows on coarse pointers.

Sizing the board wrapper to a 3:2 aspect ratio and letting the canvas fill it, with the cell size recalculated from the 24×16 grid on each resize.

I'm settling the board's size: width capped at the smaller of the full container or the viewport height minus the header space times 1.5, so the 3:2 board fits on short screens without scrolling. I'm weighing whether `vh` is safe on mobile, since the 100% cap already limits the width there anyway.

Writing the responsive width rule now: capping the board at 1.5× the space left under the header, with a 280px floor so it never collapses on short screens.

I'm working through the responsive layout now: a two-column grid on wide screens with the board beside the HUD, stats moving under the board on mid-sized screens, and a 2×2 stats grid on phones. I'm also deciding when the touch d-pad should appear, based on the narrow width or a coarse pointer.

I'm wondering whether the d-pad is worth including at all, since swiping already covers touch input. I'm leaning toward keeping it for narrow widths anyway, because it's harmless on desktop and gives mobile players a direct control, even if it adds some height to the page. I'll decide whether to keep it or drop it to keep the code simpler.

I'm settling how the passengers get counted: each pickup adds one wagon, so the wagon count is the passenger count. Starting length is still open, between a locomotive with two wagons and one with two empty ones, and I'm weighing whether boarded passengers should show in the windows from the start or only after pickup.

I'm weighing whether the train should start with just a locomotive or with a couple of wagons already attached. Starting with two wagons would make the snake easier to read from the first frame, and I'd count the initial wagons as starting carriages with passengers already aboard. So the on-board count would be the number of wagons, with the locomotive left out.

I'm going back and forth on the starting train: a locomotive with two empty wagons, or one with three, since starting length matters for readability. I'm leaning toward empty wagons with dark windows so pickups visibly fill them, but I'm unsure whether that loses the charm of passengers from the first frame. The HUD count is getting tangled too, so I'm considering counting only pickups as passengers and showing train length separately.

I'm weighing whether the starting wagons should already hold passengers, since that would make the first frame feel alive, or whether they should stay empty so the counter starts clean at zero. Either way, the new wagons from each pickup will carry a passenger, so I just need to settle what the opening train looks like and what the counter shows at the start.

I'm settling on a starting train of just a locomotive, with two empty starter wagons whose windows stay dark until pickups fill them with passengers in matching colors.

Starting the train with a locomotive and two wagons that already carry passengers would make the opening frame feel alive. The HUD count would then be body length minus one, starting at two, while the score tracks pickups separately. I'm noticing a gap, though: if the train ends and the HUD still says "aboard," nothing actually delivers those passengers yet, so I'll need to decide whether a terminal or delivery step belongs in the design.

I'm weighing whether a delivery mechanic, where passengers ride to matching stations and get unloaded, would add enough fun to justify the extra complexity. It would be a bigger design change, and the user only asked for pickups, so I'm leaning toward keeping it pickup-only. I'm also settling the starting train as a locomotive with two empty wagons whose windows stay dark until passengers board at the tail.

I'm leaving the passenger count as pickups only, so the HUD can show passengers, level, score, and best without a separate wagon count to explain.

I'm settling on a score that combines a flat 10 points per passenger with a small express bonus for picking someone up early in their wait, so speed is rewarded without making the scoring hard to follow.

I'm turning to the station platforms next: each one gets a small sign with a name like "Pinewood" or "Harbor," drawn at the end cap as flavor text.

I'm laying out the station platforms on the 24×16 grid, placing a few three-cell segments as passenger spawn zones. Platform cells stay walkable for the train, which I'll justify as track running through the station with platforms on either side. Visually I'll draw them as concrete with yellow edges.

I'm picturing the board as a meadow of grass with subtle light and dark patches, and I'm not sure yet whether to add dirt paths or faint dashed lines to break it up.

I'm now sketching the look of the board: canopied trees, cottages with red roofs, grey rocks, and flower dots on the grass. The border will be a brown frame drawn in CSS rather than cells, so only the playable area counts for collisions. Platforms will be pale concrete with a yellow safety strip along the edge.

I'm working out the station name signs now: a small plate on the platform's first cell with the station name, while lamp posts mark the ends. I'm weighing whether floating signs above the platform would collide with neighbouring trees, and I'm leaning toward keeping the plate inside its own cell so it stays clear of obstacles.

I'm sketching the station side of the board now: lamp posts at the ends, maybe a small sign plate on the first cell, though text could be unreadable on a 375px screen, so I'm leaning toward a plain unlabeled plate and only adding names if the cells are large enough to hold them.

Still working out the color scheme, now choosing a palette of distinct wagon and passenger colors that won't clash with the locomotive.

I'm working through the game's data layout and how the snake train's movement and passenger logic will be structured, with the grid set at 24 by 16 cells.

Still laying out the game's data: an obstacle grid, platform flags, the train body as a list of cells from head to tail, a queued direction so two quick turns can't reverse the train, and timers for stepping, passengers, and particles.

I'm working out how the train's body will be stored and drawn: the segments run from head to tail, and between steps each one slides from its previous cell to its new one so the motion stays smooth. The tricky part is that the body array changes length whenever a passenger boards, so I need to handle the new tail segment without it jumping.

I'm settling how the body moves: before each step I'll save the current segment positions, and after the step each segment takes the spot of the one ahead of it. When a passenger boards, the new tail segment has no saved position, so it simply appears at its current cell without sliding in.

I'm working out how the body moves: each segment should take the position of the one ahead of it, so a segment shifts from its old cell to the cell its predecessor vacated, and I need to make the interpolation match that.

Now I'm working out how the body moves: the head steps into the new cell, and each segment after it takes the cell of the segment just ahead, so the segment that was at index k-1 ends up at k. I need the interpolation to follow that same mapping.

I'm working out how the body interpolates: each car k starts at its old cell and slides into the cell that was in front of it, so the render needs to follow that same mapping before I store the previous positions.

I'm working out what happens to the tail when the train grows: the new segment has no earlier position to slide from, so I'm checking where it should appear relative to the old tail.

I'm checking how each body segment's interpolation maps: a segment that was at the old tail gets no earlier position when the train grows, so it simply appears where it is. For every other segment, the start point is its old cell and the end point is the cell that was in front of it, so the slide lines up with the body's array mapping.

I'm checking the tail case: when the train doesn't grow, the last car moves from its old cell into the one ahead of it, so it slides forward like the others.

I'm checking the grown-tail case: the new car has no earlier cell, so it appears at the old tail's position, while the car before it slides forward out of that same spot.

I'm settling how the locomotive and wagons should rotate as they slide: the head will use the current movement direction, and each following car will face the car in front of it, computed from the interpolated positions so the turns look smooth.

I'm settling how the rotation will work for the wagons: each one can face the car in front of it, taken from the post-step positions, so the turns snap at the step boundary. I'm weighing whether to smooth that snap by interpolating the angle instead, since at corners the rotation would otherwise jump while the car is still moving.

I'm weighing whether wagons should rotate at all or stay unrotated squares. Rotated oblong wagons would read as one connected train on straight runs and bend naturally at corners, so I'm leaning toward that over the snapping risk.

I'm using the interpolated positions to derive each wagon's forward direction: the difference between a car and the one ahead is a blend of the old and new orientations, so the rotation turns smoothly through corners instead of snapping at the step boundary.

I'm working out how the head's heading should interpolate: lerping from the previous direction to the current one over the step gives a smooth turn, instead of a snap at the step boundary. Then I'll store the previous direction so the head can use it, and I'll figure out how each wagon's rectangle gets its angle from the interpolated forward vector.

I'm settling on the wagon rotation: rather than snapping each wagon's angle at the step boundary, I'll interpolate its forward direction between the old and new orientations, which keeps turns smooth through corners. The code gets a bit longer that way, but I'm weighing that against a simpler fixed-direction version that might look slightly jerky when the train turns a corner.

Next I'm settling how the wagons' positions interpolate along the grid: each car moves straight between adjacent cell centers, so the path stays axis-aligned and never cuts a diagonal across a corner. The locomotive's wheels can just advance by distance traveled each frame.

Now I'm working out the smoke: puffs come from the chimney near the front of the locomotive and drift backward, opposite the direction of travel, so they trail behind the moving train. Each puff needs a position, velocity, radius, life, and color, and I'll cap the count around 120 so it stays light.

I'm sketching the locomotive's look now: a dark red body with a lighter boiler stripe down the middle, a darker cab at the back with a light blue window, and a dark chimney at the front. I'm also planning a dark cow-catcher and a glowing yellow headlamp at the very front, four wheels whose spokes turn with the wheel phase, and a brass trim stripe.

Still writing the wagon drawing code...

Still writing passenger sprites...

Still writing the passenger timer bars and the static background layer...

Now I'm sketching how the game's overlays and state transitions will work: the demo AI steers the train until the player starts, and a brief "Derailed" message will show before the demo restarts.

I'm sketching the demo-to-play flow now: the AI keeps steering until the player's first input, and a crash in demo mode just restarts the demo after a short pause. After a play-mode crash I'll show the game-over overlay, then drop back to the demo if the player stays idle for about nine seconds.

Now I'm working out how the demo AI should steer, so the train reaches a couple of waiting passengers within the first few seconds and the opening screen looks lively. I'm starting the head around the middle-left of the board, heading east with the body trailing west, and placing obstacles so they don't block the early route to the nearest platforms.

Next I'm placing the four platforms at random, each three cells long and horizontal or vertical, keeping them clear of obstacles, each other, and the starting area. Obstacles fill roughly 6–8% of the open cells, mostly trees, with some rocks and houses. After generating the map, I'll flood-fill from the start to confirm most free cells are reachable, and regenerate the obstacles if not.

I'm setting passenger spawning: a random free platform cell, with a new passenger every couple of seconds up to a cap that rises with level. Three start at once so the first screen has people waiting, and each one lasts about sixteen seconds before leaving, a little less as levels climb. They pop in with a scale-up animation.

Pickups are handled by checking whether the new head cell holds a passenger: if so, that passenger is removed, a car in its color is added at the tail, the score goes up, and a popup, sound, and sparkles fire. Every fifth passenger bumps the level and shortens the step interval, and the tail stays put for that step so the train actually grows.

Still working out the step function: the new head position gets checked for walls, obstacles, and the snake's own body, with the tail allowed to vacate only when the train isn't growing.

Now I'm working out how the AI picks a direction, starting from a blocked grid that marks obstacles and the snake's body. I'm still deciding whether to treat the tail as blocked too, which keeps things simple but costs the AI a cell it could use next step.

Still working out the AI's direction choice: for each legal move I'm checking whether it leads into a dead end, using a flood fill to count reachable space, and measuring how far it is from the nearest passenger.

I'm scoring each legal move by how close it brings the head to the nearest passenger, balanced against how much open space it leaves, so the AI avoids dead ends. I'm still working out how to measure the distance to the target from each candidate cell.

I'm settling on the AI's scoring, where each candidate move is ranked by its distance to the target plus penalties for dead ends and tight space, minus a small bonus for open room. The lowest score wins, and if no move is legal the train just keeps its current heading and crashes. I'm also wondering whether the greedy distance approach could trap a long train, so I'm considering a reachable-tail check after each candidate move.

I'm checking whether the tail stays reachable from the candidate head, treating the tail cell as free for that flood fill since it will vacate. If it can't be reached, that move gets a penalty, and I still need to settle whether the passenger BFS should treat the tail as blocked.

Tail-cell safety: the tail only vacates if the snake isn't growing this step, so stepping onto it is fine unless the target cell holds a passenger, in which case it's a collision.

I'm working out the tail-collision rule for the candidate move: the new head can enter a body cell only if it's a non-tail segment, or the tail when no passenger is there. For the flood fill, I'm building an occupancy grid from the post-move body, leaving out the tail when the train isn't growing.

Now I'm settling how the candidate's reachability gets measured: one BFS from the candidate over the post-move occupancy grid, counting reachable cells, noting the nearest passenger, and checking whether the tail is reachable.

Still writing the scoring code...

Working out the demo AI's scoring is turning into a question of how much open space to reward. I'm settling on counting reachable cells from each candidate move and skipping any cap, since the grid is small enough for a full flood fill. If nobody is waiting, the AI will lean toward open room instead of chasing a target.

I'm settling how the demo mode and the player mode differ: the demo just runs the AI at normal speed so it's easy to watch, while the overlay asks for a click or key press to start a real game. Input will be caught on the window itself, since the canvas may not have focus.

I'm deciding how input gets handled: any arrow, WASD, space, or enter key starts a real game from the demo or restarts after a crash, with a short 0.6-second cooldown after a crash so a stray keypress doesn't immediately restart. Clicks on the board or the overlay should count as a start too, so I'm binding pointer events there and considering whether clicks anywhere on the page should work as well.

I'm settling input handling now: a document-level pointer handler will count as a start, with the d-pad buttons sending their direction, and each handler will be written so that running it twice does no harm. For the board, I'm planning swipe detection, where a drag over 24 pixels sets the heading and a plain tap starts the game if it isn't already running.

I'm deciding how the sound layer works: an AudioContext gets created on the first user gesture, with a square or triangle toot that sweeps in pitch, a sine ding for passengers, and a short noise burst for crashes, all wrapped in try/catch. I'm leaning toward starting with sound unmuted and giving the HUD a Sound on/off toggle.

I'm settling the sound layer: audio only starts after the first user gesture, and the demo stays quiet until then. Once the game is running, a toot marks departure, a two-tone chime plus a tick marks a passenger pickup, and a noise burst with a falling tone marks a crash.

Now I'm laying out the page structure: a header with the title and a demo/play mode pill plus a sound toggle, then a main area holding the board with its start overlay.

Still writing the page markup...

Still writing the page markup...

Still working out the visual design: I'm weighing a dark night-time page against a light storybook look, and leaning toward dark for the bright train to stand out. I'm picking a navy gradient background, yellow and teal accents, and a system font stack.

Now I'm settling the look: a rounded display font for the title, a wooden board frame with rounded corners and a soft shadow, and a translucent dark overlay card with a blinking yellow prompt. A short toast will fade in at the top of the board to announce level changes, and then I'll start on the canvas drawing code.

Still working out the canvas sizing: I'm reading the wrapper's width to set the drawing size and planning to keep the board at a fixed aspect ratio.

Still sorting out the canvas sizing: I'm taking the smaller of the width and height per cell, centering the grid with offsets, and filling the rest with the background colour so the aspect ratio can't break things.

Still writing the canvas drawing code, with the grid offset for the board's background and the static obstacles and platforms.

Still writing the canvas drawing code: I'm drawing each tree in its cell, with a soft shadow, a brown trunk, and layered green canopy circles.

Still writing the canvas drawing code: I'm drawing the houses and rocks as shaded shapes, and I'm building the platform cells on a concrete base with yellow edges.

Still writing the canvas drawing code: I'm finishing the platform edges, marking a yellow strip on any side that doesn't touch another platform cell.

Still writing the canvas drawing code: I'm moving on to the per-frame render loop, which first draws the cached background and then switches the transform to scale for the dynamic layer.

Still writing the dynamic render pass: the passengers go down first, then the train cars with a flat offset shadow under each one before the bodies are drawn, then smoke and popups on top.

Still working out how the train's body segments move between steps, so each car can be drawn sliding smoothly from its previous position to its new one.

Still working out how each car's previous and current forward direction get compared, so the drawing can blend between them as the train moves.

Still working out the interpolation for the train: each car's grid position is lerped between its previous and current spot, then converted to pixels at draw time. I'm capping the catch-up steps per frame at three so a long pause doesn't stall the render.

Still writing the locomotive drawing, sized off the cell and rotated to face its heading.

Still writing the locomotive: the wheels, the red body, and the darker shading toward the bottom edge.

Still writing the locomotive: the chimney goes on the front of the boiler, and the cab gets a light blue window on its roof.

Still writing the locomotive details: the dome, the headlamp with its glow, the cowcatcher at the front, and the gold stripes along the body.

Still writing the wagon body: I'm laying out the wheels, the roof band, and the window row with a head shown in one of the windows.

Still working out the carriage look: I'm drawing the wagons from above with side-style windows, and I'm adding a head in a window with hair and skin colours picked at random. A lit window will glow warmly when a passenger is aboard.

Still writing the passenger sprite: a shadow at the feet, a shirt-coloured body, one arm raised and waving, and a skin-toned head with hair on top.

Still writing the passenger sprite: the waiting bubble above the head, the suitcase beside them, and a pulsing glow ring under each one to draw the eye.

Still working out how the train's pixel positions get computed: I'm mapping grid cells to screen coordinates with a fixed cell size and half-cell offset, and I'm making sure the shake only nudges things by a few pixels as it fades.

Now I'm wiring up the HUD so the score, passengers, level, waiting count and best all update only when something actually changes. Then I'll set up the overlay helpers, the demo title screen and the game-over message showing passengers picked up and score.

Now I'm deciding the demo overlay should stay small so the train's action stays visible around it. The best score should only count real player runs, not the demo, so the HUD can't show demo numbers that look like progress.

Now I'm setting up the d-pad controls: four arrow buttons drawn as simple inline SVG triangles so they don't depend on font glyphs.

Now I'm mapping the keyboard controls: the arrows and WASD set the four directions, and Space or Enter starts the game. Pressing an arrow while on the game-over screen will restart and set the starting heading, with the body trailing behind it.

Now I'm settling the startup behaviour: the game always begins heading east, since placing the body behind a different starting heading would be more trouble than it's worth. A valid first key press will then queue a turn, and a restart from the game-over screen or the demo follows the same rule.

Now I'm working out the progression numbers: level goes up every five passengers, and the step interval tightens as the level rises, bottoming out around 68ms. I'm also setting the passenger timers to shorten with level and keep the spawn gap roughly between 1.6 and 3 seconds.

Now I'm settling the passenger rules: at most one passenger per platform cell, and with 4 platforms of 3 cells each there are 12 cells, which is plenty for 3 to 6 waiting. I'm also deciding the scoring: each pickup is worth 10 points, and I'm weighing whether to add an express bonus for early pickups, leaning toward keeping it simple at 10 points.

Now I'm settling the passenger bonus: a pickup counts for 10 points, or 15 with a "quick!" label if the passenger was collected while most of their wait time was still left. The passenger giving up when their timer runs out costs nothing, though I'm thinking of showing a "Missed" note at the platform.

Now I'm wrapping up the HUD and overlay logic: the best score only tracks real player runs, and a crash sets the state to game over and updates the best display.

Still writing the page's base styles: the palette variables, the box sizing, and a gradient background with no horizontal scrollbar.

Still writing the page layout: a grid with a flexible board column beside a fixed-width side panel, collapsing to one column on narrow screens.

Still working out the board sizing: the board's width is capped by the viewport height so it fits at 1280×800, and I'm checking the column math against the side panel width.

Still working out the board's border: I'm giving the frame a wood-coloured border and letting aspect-ratio hold the 3:2 shape with the border counted in, then pinning the canvas inside it.

Now I'm laying out the board's frame: a wood-coloured border with padding and rounded corners, wrapping an inner stage that holds the 3:2 aspect ratio and clips its contents.

Still sizing the board frame: I'm capping its width so the stage keeps its 3:2 shape and fits the viewport height, with the wood border added on top.

Now I'm sizing the stage so it keeps its 3:2 shape, with the canvas filling it absolutely and the side panel holding the stats.

Still writing the header's right-hand side: a pill labelled as the demo AI driver, plus a sound toggle button.

Still writing the page's header and board frame styles: the pill and live-badge looks, then a wood-coloured rounded border whose width is capped so the inner stage keeps its 3:2 shape within the viewport height.

Still writing the stage styles: a relative box with a 3:2 aspect ratio, rounded corners, clipped overflow and green background, with the canvas filling it absolutely.

Still writing the overlay styles: a full-stage grid that fades out when hidden and ignores pointer input, with a dark translucent card for the messages.

Still writing the overlay styles: the card's padding, heading and message sizing, a pulsing message, and a blink keyframe.

Still writing the toast styles: a centred pill that fades in, sitting at the top of the stage and truncating long text.

Still writing the side panel styles: a flex column with gaps, stat cards with small uppercase labels and large tabular numbers, and a two-column grid for the stats.

Still writing the responsive rules: the side panel switches to a two-column grid on narrower screens, with the big score card spanning both columns.

Still writing the side panel: I'm switching it to a two-column grid, with the big score spanning both columns and the how-to box spanning them too. The D-pad will be hidden on wide screens and shown below the board on mobile.

Still writing the responsive rules: the D-pad is laid out as a three-by-three grid with the up, left, right and down buttons around an empty centre, and it appears only on narrower screens.

Still writing the D-pad styles: a three-by-three grid with the up, left, right and down buttons around an empty centre, shown only on narrower screens or touch devices.

Still writing the canvas setup: sizing the drawing surface to the stage at device pixel ratio, with a matching offscreen background canvas.

Still writing the resize logic: the drawing surface is sized to the stage and the playfield is centred inside it, with the background rebuilt on each resize.

Still writing the world generator: it retries up to 60 times, marking a reserved start zone and placing platforms until there are enough.

Still writing the platform placement: it tries up to 200 random horizontal or vertical runs of three cells, skipping the reserved start zone and anything already taken, and keeps a one-cell gap from other platforms.

Still writing the world generator: each platform attempt is checked against the start zone and existing platforms, and I'm keeping a one-cell buffer from any platform already placed.

Still working on the world generator: I'm checking that every free cell can be reached from the start by flood-filling from the head position, since random obstacles could wall off a corner, and I'm deciding whether to retry or clear the isolated pockets.

Still working out the world generator: I'm adding scattered obstacles like trees, rocks and houses, then checking that every free cell can still be reached from the start, and retrying if a pocket gets walled off.

Still writing the world generator: I'm deciding how the station platforms and their edges should look against the grass and trees, and I'm considering a few small decorative details before settling on the visual style.

Still writing the game's start state: a fresh random world each run, with the snake train starting as a head and two wagons, plus the movement and queue variables.

Still setting up the reset: the starting train goes at the centre-left with a head and two wagons, and the start area needs to stay clear of obstacles and platforms.

Still working out how the train's cars are tracked: I'm planning a parallel array of car objects, each with its colour and passenger details, lined up index for index with the body cells. Picking up a passenger would append a new car at the tail, but I'm still thinking through how the array should shift when the train grows at the head.

Still working out how the cars stay in sync: each index keeps its own car data as the train moves, so growth just appends at the tail, and when the train doesn't grow I'm dropping the last body cell while the car data at each index stays put.

I'm checking the car bookkeeping: when the train doesn't grow, every car stays in place and the cars array keeps its length, since the tail cell is simply freed. When it does grow, a new car is appended at the tail to occupy the cell the tail just left.

Now I'm tracking the cars with a parallel array that stays aligned with the body cells: each car keeps its index as the train moves, and growth appends a new car at the tail.

Still writing the step logic: I'm checking the next head cell against the walls and obstacles, then testing whether it's a passenger so the train knows whether to grow. Self-collision is checked against the body, letting the tail cell go free if the train isn't growing, before the new head is added and the tail dropped when it doesn't grow.

Still checking the step logic: after moving the head, the body grows by one segment when eating, otherwise the tail is dropped, and the cars array keeps one entry per segment as the wagons move, with a new car appended on pickup.

Still writing the step logic: the head moves forward, the body is shifted so each car keeps its own colour data, and the tail is dropped unless the train just picked up a passenger, in which case a new car is appended.

Still writing the AI direction picker: I'm marking every occupied cell as blocked, freeing the tail cell since it moves away when the train doesn't grow, and then marking the obstacles as blocked as well.

Still writing the AI direction picker: I'm checking each candidate move from the head, skipping the reverse direction and any cell that's blocked by the body or an obstacle, and I'm deciding how to handle a candidate that holds a passenger, since the tail won't move away in that case.

Still working on the AI direction picker: I'm treating the tail cell as free for a normal move, but if the candidate cell holds a passenger the tail stays put, so I'm blocking it in that case.

Still writing the AI direction picker: for each candidate I'm checking whether it holds a passenger, since that decides whether the tail stays blocked or frees up, and I'm setting the tail cell's occupancy to match.

I'm working out the candidate moves: each one gets a fresh copy of the blocked cells, with the tail freed only when the train won't grow, and then a flood fill from the candidate counts how much room it leaves and how close the nearest passenger is.

Still writing the AI direction picker: I'm running a flood fill from each candidate to measure how much room it leaves and how close the nearest passenger is.

Still writing the flood fill: I'm checking the new head's neighbours with the candidate's own cell blocked so the search can't loop back, and I'm recording the nearest passenger distance along with whether the tail cell is reachable.

Still working on the AI scoring: I'm weighing each candidate by how close its nearest passenger is, with penalties when the reachable area is smaller than the train's length or too small overall, and a small bonus for open space.

Still writing the AI direction picker: for each candidate I'm measuring the reachable area and the distance to the nearest passenger, then adding a little random noise to the score so the snake doesn't loop.

Still tuning the AI's odds: with around 40 cars on a 24×16 grid and about 30 obstacles, the free space shrinks, so it should eventually get boxed in. I'd expect a crash somewhere in the 40 to 80 second range, then an automatic restart. I also want the demo to look good right away, so the AI should head straight for the nearest passenger in the first few seconds.

Now I'm setting up the update loop: it measures the frame time, clamps it to avoid large jumps, then runs the update and the render each frame.

Still writing the update loop: the frame advances the simulation in fixed steps, capped so a slow frame can't spiral, then updates the passengers and spawns new ones. When the snake crashes during a step, I'm stopping further steps and switching state, with a pause before the demo restarts.

Still working on the interpolation: when the snake is alive, the render position is the step fraction, and once it crashes that fraction is pinned to 1. The body is copied before each step, so a crash partway through leaves the drawn train unchanged, and the explosion particles keep animating after the loop stops moving the snake.

Still writing the spawn logic: I'm counting down a timer each frame, and when it runs out and there are fewer passengers than the cap, a new one gets placed.

Still writing the spawn logic: I'm picking a free platform cell, one that holds neither a passenger nor a body segment, and creating a new passenger there with a random colour.

Still writing the spawn logic: I'm picking a passenger's look and how long they'll wait before leaving, and I'm making sure a passenger spawned on a cell the head is about to enter still gets picked up on that move.

Still writing the pickup handler: a passenger's points depend on whether it was grabbed while still fresh, the train gains a car, and every fifth passenger bumps the level.

Still writing the crash handler: I'm stopping the snake, shaking the screen, and spawning dark and white puffs and sparks at the head. In demo mode it schedules a quick restart, and in play mode it records the best score, shows the game-over overlay, and sets a timer to switch to the demo.

Now I'm setting up how a new run starts: the demo or play mode gets selected, the world is reset to a fresh map, and the snake comes back alive. The overlay copy then depends on the mode, with the demo showing the title and the controls hint.

Still writing the input handler: when the game is already running, a direction press gets queued, and when it's the demo or a finished run, the first press starts a fresh play run, with a short lock after game over.

Still working through the input handling: the first valid direction in the queue gets applied each step, and reverse presses are skipped so the train can't fold back into itself.

Still writing the keyboard controls: I'm checking the input queue and capping it at two entries so presses can't pile up, and I'm mapping the arrow keys and WASD to directions, with M toggling sound.

Still working on keyboard input: I'm mapping the directional keys to moves and wiring up a fallback so any other key starts the game, while ignoring keys held down so repeats don't flood the queue.

Still working on the click handling: the d-pad and sound button will each take their own clicks and stop them reaching the document, so a press on them doesn't also trigger a start.

Now I'm checking whether a click on the sound button should also start the game. The d-pad handler runs first and the document-level handler then runs too, but calling it twice does nothing harmful once the state is already play.

I'm checking whether clicking the sound button should also start the game. I'll have it stop propagation so it only toggles sound, while clicks elsewhere on the page still start the run. For the stage, a swipe will pick a direction and a tap will start, but the document-level handler has already started the run on pointer down.

Working out how the swipe and tap inputs hand off to the game: a pointerdown on the document already starts the run, so a swipe on the stage just needs to queue its direction on pointerup. Over-state presses still start a fresh run first, so that case holds too. I'm also planning a short input lock after a crash so stray key presses don't restart the game straight away.

Still writing the keyboard lock: holding an arrow key through a crash could restart the run once the lock expires, and I'm accepting that as fine. The first keypress in the demo also has to create the audio context, which works because a keydown counts as a user gesture.

Still writing the audio setup: I'm creating the audio context and a master gain at a modest volume, guarded in case the browser doesn't support it. Then I'm defining a tone helper that builds an oscillator with an envelope and routes it through its gain node.

Still writing the audio helpers: the sound toggle is fine, and I'm now sketching a toot with two square-wave tones that slide down slightly.

Still writing the audio helpers: I'm defining a tone-and-noise setup for the toot, the ding and the crash sound.

Still writing the background: I'm filling the whole stage with a green gradient ground as the base layer, before adding the rest of the scenery.

Still writing the background: I'm adding the ground's soft patches and a faint checker tint on the grid cells, then the flowers, platforms and obstacles on top.

Still writing the background sprites: I'm adding a shadow under each tree, with per-cell shade variation and occasional tufts so the meadow doesn't look uniform.

Still writing the tree sprite: I'm drawing the canopy as a few overlapping circles over the trunk, in three shades of green.

Still writing the platform drawing: I'm laying a concrete base with a light tone for each platform cell.

Still writing the platform edges: I'm marking the safety stripes on any side that isn't bordered by another platform cell.

I'm setting up the platform edges now: the long top and bottom sides get yellow safety stripes where no neighboring platform cell sits, while the short end caps stay plain. Vertical runs would get their stripes on the left and right sides instead.

Still working on the train's rendering: I'm defining a function that computes each car's position and forward direction from the body segments.

Still working on the train's rendering: I'm computing each car's position and forward direction from the body segments, interpolating from the previous frame.

Still working on the train's rendering: I'm now interpolating each car's visual heading, so the head turns smoothly at corners instead of snapping.

Still working on the train's rendering: for the head I'll use the current direction straight away, since it's already moving that way, while the wagons keep interpolating through the turn.

Still working on the car positions: the car right behind the head is moving along the old head's path, and its orientation turns from the previous direction to the new one over the step, so the coupling to the head stays aligned.

Still writing the train rendering: I'm computing each car's pose for the current frame, then drawing shadows, couplers, the wagons from tail to front, and the locomotive last so it sits on top.

Still writing the train rendering: I'm drawing the couplers as dark lines between each car's center and the one before it, so they sit under the bodies.

Still writing the car drawing: I'm sketching the wagon body as a rotated rectangle, with four wheels protruding from its sides.

Still writing the wagon body: I'm drawing it as a rounded rectangle with a light-to-dark gradient, skipping spokes on the wagons since only the locomotive gets them.

Still writing the wagon windows: I'm placing two rounded windows on each car's body, sized to fit within the body's width.

Still working on the wagon windows: I'm making the window fill warm and lit for rider cars and dark otherwise, with a head drawn in the front window.

Still writing the locomotive: I'm sketching its wheels with spokes that turn with the wheel angle, a cowcatcher at the front, and a body that's wider than a wagon.

Still writing the locomotive details: I'm adding the boiler, cab, chimney, brass dome and a glowing headlight, plus gold pinstripes along the body.

Still working on the locomotive: I'm adding its smoke, where puffs spawn at the chimney and drift back along the train as they grow and fade.

Still working on the locomotive: I'm animating its wheel spokes so they turn with the distance traveled, and updating the wheel angle each frame while the train is moving.

Still working on the locomotive wheels: I'm drawing each wheel's spokes as two crossing lines that rotate with the wheel angle.

Still writing the popups: I'm drawing the score text in bold with a dark outline so it reads over the scenery, and it rises and fades out.

Still writing the passenger sprites: I'm drawing each waiting passenger with a pop-in scale, a small bob, and a glowing ring beneath them.

Still writing the passenger sprite: I'm drawing a glow ring at its feet, a suitcase, and a shirt-colored body rounded at the corners, with legs added below.

Still writing the passenger sprite: I'm finishing the timer bar above each waiting passenger, shrinking it as their time runs out and switching its color from green to amber to red, with a blinking alert near the end.

Still writing the passenger sprite: I'm adding a suitcase beside each figure, then a waving arm raised from the shoulder. A faint pulse ring sits under them so waiting riders stand out on the platform.

Still working on the render loop: I'm clearing the canvas and applying a random screen-shake offset while the background is drawn.

Still writing the HUD: I'm refreshing the waiting-passenger count on a timer every quarter second, rather than on each spawn or expiry.

Now I'm laying out the side panel: a large score figure across the top, then passengers and level, then waiting and best, with the controls explanation at the bottom.

Still writing the header: I'm adding a small inline SVG train logo and a short subtitle that says the snake is a little train with passengers waiting on the platform. Then I'll write a rounded-rectangle path helper for the drawing code.

Still writing the helpers: I'm adding a hash function that gives each grid cell a stable pseudo-random value, so the background decorations don't shift between frames.

Still writing the helpers: I'm adding a small hash that gives each grid cell a stable pseudo-random value, using integer multiplication so the results stay consistent, plus random helpers for numbers and picking from arrays.

Still writing the color palettes: I'm choosing a wagon palette without red so it doesn't clash with the locomotive's dark red, and the passenger shirts will reuse the same colors.

Still working on the step logic: I'm tracking the passengers the train has to pick up as it moves.

Still writing the game loop: I'm snapshotting the body for interpolation, then taking the next queued turn that doesn't reverse direction, or letting the AI pick one in demo mode.

Still writing the game loop: I'm collision-checking the new head against the walls, obstacles and the body, skipping the tail since it moves away, then pulling any passenger on that cell onto the train.

Still writing the crash handling: when a move would hit a wall or obstacle, the head stays put and the crash effect plays at the head's cell, with a puff aimed at the blocked cell.

Still writing the board function: I'm adding the passenger as a new car, scoring more points if they boarded while their timer was still above 60%, and showing a popup and sparks.

Still writing the game logic: I'm adding the passenger as a new car, scoring extra points if they boarded while their timer was above 60%, and then checking whether the level should go up.

Still writing the crash handling: I'm setting a shake and an explosion at the head, and in demo mode scheduling a restart.

Still writing the crash handling: I'm setting a delayed restart in demo mode, and in a real run I'm marking the game over, saving the best score, and showing the overlay with the passenger count and score.

Still writing the game loop: I'm starting a run in either demo or play mode, which resets the world, rebuilds the background, and places the snake's starting body.

Still writing the game start: I'm resetting the snake body, direction, queue, score, and level, then spawning three passengers on the platform.

Still writing the game start: I'm finishing the reset with the world rebuilt and the overlay shown or hidden for demo versus play, then setting the spawn timer and placing the initial passengers.

Still writing the world generation: I'm building a tryWorld helper that places obstacles and platform cells on the grid, and generateWorld will retry it until the layout is connected.

Still writing the world layout: I'm placing platform segments on the grid, keeping them clear of the train's starting area and away from one another.

Still writing the world layout: I'm placing obstacles on the grid while keeping the platform cells and the train's start area clear.

Still writing the world layout: I'm placing obstacles on a random pass over the grid, skipping the platform cells and the start area, and I'm also keeping a clear margin around each platform so the train can reach passengers from the side.

Still writing the world layout: I'm checking that the open cells all connect back to the start, retrying the layout if some pockets are cut off.

Still writing the d-pad: I'm adding a small on-screen directional control for touch, sitting beneath the canvas on narrow screens.

Still writing the d-pad: I'm laying out a small directional control with four arrow buttons, and I'm using an inline SVG arrow rotated by a CSS variable for each direction.

Still writing the event handlers: I'm wiring the d-pad buttons to send their direction on press, and setting up pointer tracking on the stage for swipe gestures.

Still writing the pointer handling: I'm storing where the touch starts, and on release, if the drag is long enough, I'm turning the swipe's dominant axis into a direction and queueing it.

Still writing the HUD: I'm setting up a small helper that updates a text element's content by id.

Still writing the HUD: I'm setting up the text updates for score, passengers, level, waiting count and best, and the overlay and toast helpers for titles, messages and short notices.

Still writing the HUD: I'm defining the toast helper so it shows a short notice and clears itself after a timeout.

Still writing the game loop: I'm setting up the timing for each frame, then moving the simulation forward by the elapsed time.

Still writing the game loop: I'm clamping the frame time, advancing the clock, then updating and drawing the frame.

Still writing the game loop: I'm adding the frame's wheel rotation and a smoke timer that emits puffs on a fixed interval while the train is moving, then pausing the timers when it's crashed and restarting demo or the auto-demo once their delays have passed.

Still writing the smoke: I'm working out where the chimney sits by taking the locomotive's pose at the current interpolation point, so puffs can come from there.

Still writing the smoke: I'm adding a puff at the chimney's position, drifting it backward and slightly upward as it grows.

Still writing the particle system: I'm setting up the update step to move each particle and grow smoke puffs over their lifetime, then drawing smoke as translucent circles and sparks as small fading dots.

Writing the AI driver logic...

Scoring each possible move for the AI driver: I'm computing a blocked grid from the obstacles and the train's own body, marking passenger cells, and checking the tail cell.

Still writing the AI driver: I'm scoring each candidate move by flood-filling the free cells from the new head position, which means copying the blocked grid and clearing the tail cell unless the train picks up a passenger.

Still writing the AI driver: I'm scoring each candidate move with a breadth-first flood fill over the free cells, counting how much space it opens up and how close the nearest passenger is.

Still writing the AI driver: I'm scoring each candidate move by how much open space it leaves, whether the tail stays reachable, and how close the nearest passenger is, with a small random nudge on top.

Scoring each candidate move now: the AI counts how much open space each one leaves, and flags the case where the tail can't be reached.

I'm checking that the tail cell is freed when the train isn't growing, and that the demo AI doesn't reverse onto its own body. Then I'm estimating the difficulty curve: three passengers at a time, roughly 8.5 cells per second at level one, with the step time dropping as levels rise.

Still writing the passenger rendering: I'm making the figures a bit larger, with the head radius set to about 0.17 of a cell.

Still writing the passenger and wagon sizes: I'm making the wagons wider and the windows larger, with the passenger heads sized to stay visible at the cell scale.

Still writing the train's car drawing: I'm sizing the cars and locomotive slightly larger, then drawing each car as a rotated shape, starting with the shadow.

Still writing the car drawing: I'm drawing the wheels as small rounded rectangles on each side of the car body.

Still writing the car drawing: I'm sizing the body with a vertical gradient that runs from a lighter shade of the car's color down to a darker one, then adding the wheels as rounded rectangles that stick out past the top and bottom edges.

Still writing the car body: I'm filling a rounded rectangle with the vertical gradient, then adding a light stripe along the roof.

Still writing the car body: I'm adding the windows and the passenger heads inside them, then the couplers between cars.

Still writing the car body: I'm drawing the windows as rounded rectangles along each side, then starting a rider's head inside the first window.

Still writing the car drawing: I'm adding a head at the rider's window, with a skin-colored face and hair, while I work out the head drawing helper.

Still writing the head: I'm drawing the hair as the top half of the head circle, using an arc from π to 2π.

Still writing the locomotive: I'm drawing its wheels with spokes, starting with the front pair.

Still writing the wheels: I'm drawing each wheel as a dark rounded rectangle, then adding spokes rotated by the wheel angle.

Still writing the locomotive: I'm adding the cowcatcher at the front and the main body, then working on the gold pinstripes along its side.

Still writing the locomotive: I'm drawing the pinstripes along the body, then the rear cab with its light blue window, and finally the central boiler.

Still writing the locomotive: I'm adding the brass dome and the chimney, then the headlamp at the front.

Still writing the locomotive: I'm placing the headlamp at the front of the body and the chimney further back, with the dome sitting between them.

Still writing the headlamp: I'm placing the chimney toward the front of the boiler and moving the headlamp slightly forward so the two don't overlap.

Still writing the locomotive: I'm placing the headlamp at the front and giving it a faint glow, then coloring the body with a red gradient and adding a dark stripe.

Now I'm sorting out the draw order: background first, then the waiting passengers, then the train, then particles and popups on top. I'm also checking whether a passenger could end up drawn under the train, which should only happen briefly while the head steps into a passenger cell.

Now I'm settling how a passenger gets picked up: the head reaches the cell, the passenger is removed right away, and it's fine if that happens a touch early during the move. For the boarding effect, I'll keep it simple with a sparkle and a popup rather than animating a figure into the last car. Last, I'm sketching the demo overlay at the center: a "Snake Express" heading and a line asking the player to click or press a key to start.

Now I'm checking the demo's first moments: the AI should be moving and picking up passengers, with the smoke trail and title card both visible. I'm also making sure the pickup logic holds up with obstacles and waiting passengers, and that a passenger is never spawned on a cell the AI is about to step onto.

Checking the start conditions next: the train begins at (3..5, 8) facing east, and the start zone keeps obstacles out of cols 1–8 in rows 5–11, so there's a clear run of a few cells before anything can be hit. I'm also wondering whether an obstacle might sit in row 8 just past column 8. Crash detection checks obstacles only, not passengers. If the player does nothing, the train could reach the wall within a few seconds, so I'll need to make sure that's acceptable.

I'm going over the timing: the train starts east at column 5 with 24 columns, so the wall is about 18 cells away, roughly two seconds before it would crash if the player does nothing. I'm treating that as acceptable, since the overlay waits for a click or keypress before anything moves. Next I'm planning the game-over state, showing a "Derailed!" message with the final passenger count and score.

Now I'm weighing whether the headlamp, chimney and boiler positions overlap, and adjusting them so the chimney sits at the front of the boiler and the headlamp just past it.

Now I'm laying out the page styles: a dark navy background with soft radial glows, and a text font stack that falls back to system fonts.

Still writing the stylesheet: I'm styling the top bar with its brand block, logo, and heading.

Still writing the stylesheet: I'm styling the pill badges and the button, with the accent colors for the live and game-over states.

Still writing the stylesheet: I'm styling the board frame with its wooden border, width scaled to the viewport height, and a deep drop shadow.

Still writing the stylesheet: I'm styling the overlay so it sits over the board and fades out when the game starts.

Still writing the stylesheet: I'm styling the overlay card with its centered text, rounded frame, and blurred backdrop.

Still writing the stylesheet: I'm styling the toast notice as a rounded pill that floats at the top of the board.

Still writing the stylesheet: I'm styling the toast's text and the side-panel stat cards, with a wide card spanning both columns.

Still writing the stylesheet: I'm styling the stat cards' labels and numbers, with a larger accent value for the big score and a how-to panel spanning both columns.

Still writing the stylesheet: I'm finishing the mobile breakpoints, with the side grid switching to two columns and the d-pad showing up below the board.

Still writing the stylesheet: I'm adjusting the board frame so its width is capped by the viewport height on every screen size, keeping it from overflowing on short landscape phones and tall portrait ones.

Still writing the mobile layout: on narrow screens the board stretches to the full width, with the stat cards arranged in two columns below it.

Still writing the markup: I'm adding the logo's little locomotive shapes and a brand header.

Still writing the logo: I'm adding the wheels and a yellow base line under the locomotive shapes.

Still writing the logo: I'm adding the wagon shapes and their colors to the train icon.

Still writing the logo: I'm adding the wagon shape and the locomotive body with its smokestack and cab window.

Still writing the HTML markup: I'm finishing the logo's locomotive and wagon shapes, then laying out the main section with the game board frame, canvas, and start overlay.

Still writing the markup: I'm adding the toast container and the dpad placeholder, then the side panel with its score, passenger, level, waiting, and best-run stat cards.

Still writing the markup: I'm adding the how-to list with its three tips about passengers, patience timers, and derailing, then a keys line with the controls.

Still writing the script: I'm setting up the constants for the board size, the direction vectors, and the carriage palette that passengers will also use.

Still writing the script: I'm setting up the DOM references for the stage, canvas, overlay, toast, and HUD elements.

Still writing the script: I'm declaring the game state variables for the snake position, direction, passengers, score, and the speed timer.

Still writing the script: I'm defining the small helper functions for random numbers, clamping, and indexing.

Still writing the helpers: I'm adding the color mixing function and light and dark shade shortcuts.

Still writing the helpers: I'm adding the constructors for carriages and the locomotive, plus the passenger skin and hair palettes.

Still writing the background: I'm filling the meadow with a green gradient and then scattering cell variation and grass tufts over it.

Still writing the background: I'm filling the meadow with blurred radial patches of light and shade so it doesn't read as a grid.

Still writing the background: I'm adding the small grass tufts across each cell, then the flowers and the platform and obstacle shapes.

Still writing the tree drawing: I'm adding the canopy blobs and trunk over a soft ground shadow.

Still writing the tree drawing: I'm layering a darker canopy, then a lighter highlight pass offset up and to the left, and a small glint on top.

Still writing the tree drawing: the lighter canopy pass is done, so I'm drawing the rock next, with its shadow under it.

Still writing the house drawing: I'm laying out its shadow and starting the walls.

Still writing the house drawing: I'm sketching the roof as a red rectangle with a ridge line down its middle, then a small door at the bottom.

Still writing the drawing code: I'm sketching the house's roof as a dark-red block with a lighter ridge line and a small grey chimney.

Still writing the draw loop: I'm clearing the canvas, adding a screen-shake offset when it's active, and drawing the cached background at that offset.

Still writing the draw loop: I'm working out the screen-shake offset, which will be applied in device pixels so the background shifts correctly at any scale.

Still writing the draw loop: I'm offsetting the cached background by the shake amount, applying that same offset to the canvas transform so the world shifts together with it.

Still writing the draw loop: I'm wiring the train to be drawn from interpolated positions between the previous and current body, then the particles and popups on top.

Still writing the train: I'm drawing the couplers as dark lines between each car's center, with rounded ends.

Still writing the train: I'm drawing the shadows for every car in one pass and the car bodies in a second pass on top, so the couplers stay hidden under the cars.

Still writing the drawing loop: I'm setting each wagon's shadow and body together, starting from the tail and ending with the locomotive, and I've decided that the overlap between shadows and neighboring cars is fine.

Still writing the passenger drawing: I'm setting the pop-in scale, the bobbing and waving offsets, and the fading lifetime. Then I'm starting the outer ring, which flashes red when the passenger is about to leave.

Still writing the passenger drawing: I'm drawing the legs in a fill color next.

Still writing the passenger body: I'm drawing the legs in a dark blue, then the rounded torso in the passenger's color, and starting the waving arm.

Still writing the passenger's face: I'm adding the eyes and then the rest of the head details.

Still writing the passenger's timer bar: I'm drawing its dark background track just above the head.

Still writing the timer bar: I'm finishing its rounded background track and the color fill that shrinks as the passenger's time runs out, with a blink once it gets low.

Still writing the popups: I'm drawing each floating score text with a dark outline, lifting it upward and fading it out as its age grows.

Still writing the particles: I'm setting up the smoke puffs, which grow and drift, and the sparks that burst out of a passenger's cell.

Still writing the particles: I'm finishing the update step, which removes each puff or spark once its lifetime runs out and moves the rest by their velocity, with sparks slowing down faster than smoke.

Still writing the particles: I'm working out how smoke puffs are emitted from the locomotive, with each one growing as it ages and drifting along the train's path.

Still writing the particles: I'm emitting smoke from the locomotive's stack position, with a slight random drift and a pale fill, sized to grow as it rises.

Still writing the particle explosion: I'm spawning a burst of smoke puffs at the crash cell, each with a random outward velocity.

Still writing the particle explosion: I'm finishing the crash burst, with dark and light smoke puffs and orange sparks flying outward at random speeds.

Still writing the game loop: I'm wiring up the resize handler and making sure the background gets rebuilt with the right canvas size before the first run starts.

Still writing the game loop: I'm setting the snake's direction from either the AI in demo mode or the next queued input, skipping any move that would reverse straight back into the body. Then I'm taking the head's current position as the starting point for the step.

Still writing the game loop: I'm now setting the snake's next direction and checking that the step lands inside the board and not on an obstacle. Then I'm checking whether the head hits the train's own body, leaving out the tail unless a passenger is about to be picked up.

Still writing the game loop: I'm handling the case where the snake doesn't grow, so the tail is removed to keep the length the same.

Still writing the board logic: I'm computing the passenger's pixel position and deciding how many points to award based on how much of its timer is left, then adding a new car to the train.

I'm working out the board step: the passenger's time left decides whether the bonus counts as an express pickup, which gets a higher score and its own popup. I'm adding the car, spawning a sparkle at the pickup, and checking whether the new pax count moves the level up, showing a toast and sound when it does.

Still writing the crash handling: I'm working out how a crash ends the run, with the demo restarting itself after a short pause.

Still writing the crash handling: I'm wrapping up the crash case, showing a toast in demo mode, and in normal play switching the state to over, updating the best score, and bringing up the game-over overlay.

Still writing the userAction handler: I'm checking the game state so a key press during a run just queues the direction, while after a crash it starts a new run once the short lock has passed.

Still writing the game loop: I'm setting up the start-of-run state, placing the snake and its first car, and rebuilding the background before play begins.

Still writing the game loop: I'm setting up the start-of-run state, resetting the snake, cars, queue, score and timers, and spawning the first passengers before the demo overlay appears.

Still writing the start-of-run setup: I'm placing the snake in the first cells, and when the mode is demo I'm showing the attract overlay that explains the AI driver and the controls, otherwise hiding it and announcing the departure with a toot.

Still writing the passenger spawner: I'm filtering out cells already taken by a passenger or the train, picking a random free platform cell, and giving the new passenger a random color, look and time limit.

Still writing the passenger update: I'm setting each waiting passenger's time-to-live and planning to remove it once the timer runs out.

Still writing the passenger update: I'm making the expired passengers leave in a puff of smoke with a "left!" popup, then working out whether to spawn new ones depending on whether the run is still going.

Still writing the passenger update: I'm checking whether a waiting passenger has run out of time and, if so, removing it with a small puff of smoke and a "missed" popup. Then I'm topping the platform back up on a timer, but only while there are fewer waiting passengers than the level allows.

Still writing the game update: I'm advancing the timers, decaying the screen shake, and stepping the snake forward on each tick while it's alive, then emitting smoke from the stack at a fixed interval.

Still writing the game loop: I'm restarting the demo after a crash, and when the game is over I'm starting a new demo once the auto-restart timer runs out. Then I'm advancing the passengers, particles and HUD for this frame.

Still writing the game loop: I'm stepping the wheels and smoke on a continuous timer so they animate smoothly between the discrete snake steps.

Setting up the audio module now, starting with a helper that creates the audio context on first use and resumes it if it has been suspended.

Still writing the audio helpers: I'm creating the audio context and master gain on first use, then building the tone function that sets up an oscillator and its gain envelope.

Writing the noise burst for the crash sound...

Still writing the sound helpers: I'm working out the toot as a few stacked tones that slide down in pitch, and I'm setting up the ding next.

Still writing the sound helpers: I'm adding a "ding" that layers a bright tone with a higher overtone shortly after, and I'm setting up the crash sound next.

Still writing the event handling: I'm making the document-level pointer handler ignore taps on the sound button and the d-pad, since those buttons send their own actions.

Setting up the keyboard controls now: arrow keys and WASD map to the four directions, and M toggles the sound.

Still writing the keyboard handler: I'm checking whether holding an arrow key keeps re-queuing the same turn, and thinking about how the direction queue limits that.

Still writing the keyboard handler: I'm wiring up the on-screen d-pad buttons so each one sends its direction, and I'm checking that a press there doesn't also register as a tap on the stage.

Now I'm wiring the sound button so a tap enables audio and flips the sound on or off, updating its label to match.

Still writing the resize handling: I'm setting the device pixel ratio, measuring the stage, and sizing the canvas and background to match, then recomputing the cell size and offsets and rebuilding the background if the world exists.

Still writing the resize handling: I'm setting up the observer that re-measures the stage whenever its size changes, then kicking off the first demo run and starting the animation frame loop.

Checking whether a 375px-wide screen leaves the cells too small to read, since the stage is only about 315px across. Fewer columns on narrow screens might fix that, but it would mean the grid size changes at runtime, which adds complexity.

I'm checking whether the passenger figures stay recognizable at about 13px per cell, since they'd be only a few pixels tall at 375px wide. The board can scale down cleanly, so the real question is whether the smallest sprites still read well enough to be playable.

I'm weighing whether the grid should shrink on narrow screens so the sprites stay readable at 375px, but I'd have to make the board size change mid-run, which could push positions out of bounds on resize. I'm leaning toward keeping the 24×16 grid and accepting the smaller cells.

Still writing the world generator: I'm looping up to 80 attempts to build a layout that passes the connectivity check, and the first attempt that is connected gets used.

Still writing the world generator: I'm setting up the obstacle and platform grids, then placing platforms while keeping them away from the start area.

Still writing the world generator: I'm placing platform segments of three cells each, skipping any that touch the start area or another platform, and checking the neighbouring cells before committing each one.

Still writing the world generator: I'm checking that new platforms keep a one-cell gap from each other, then placing obstacles on the free cells outside the start area.

Still writing the world generator: I'm flood-filling from the locomotive's start cell to check that every free cell is reachable before accepting the layout.

Still writing the world generator: I'm flood-filling from the locomotive's start cell over the free cells, counting how many are reachable, and then counting the total number of free cells to compare against.

Still writing the connectivity check: I'm working out how likely an isolated pocket is near the corners, where a cell has only two neighbours, so the retry loop may need several attempts.

Still writing the connectivity check: the chance of an isolated corner pocket is low, a few percent per layout, so the retry loop should rarely need more than one or two attempts.

Still writing the background: I'm filling the canvas with a green gradient and then scattering soft darker and lighter meadow patches across it.

Still writing the background: I'm drawing grass tufts and small flowers on the free cells, skipping obstacles and platforms, with each one's details set by a hash of its position.

Still writing the background: I'm adding a small grass tuft on each free cell, and some cells get a flower too.

Still writing the background: I'm drawing the platform cells and then the obstacles on top, after the grass tufts and flowers.

Still writing the platform drawing: I'm filling each platform cell with a stone-colored slab, adding joint lines, and starting the yellow safety strip on the side that touches a neighbouring platform.

Still writing the platform drawing: I'm finishing the safety strips on the platform edges that face open ground, checking the neighbouring cells on each side so the yellow strip only appears where no other platform continues.

Still writing the obstacle placement: I'm looping over the grid and drawing a tree, rock, or house on each occupied cell, centred within it.

Still writing the background: I'm finishing the soft vignette around the edges of the stage.

Still writing the train's draw functions: I'm setting up the car pose so each wagon takes its position and heading from the segment ahead of it, and blending from the previous frame's position.

Still writing the car pose: I'm working out each wagon's position from the segment ahead of it, blending between the previous and current frame.

Still writing the car pose: for the wagons behind the locomotive I'm using the direction from the segment ahead, and I'm blending that direction with the previous frame, which should keep the turns smooth.

Still writing the train's draw code: I'm building each car's pose and then drawing the couplers between the cars.

Still writing the train's draw code: I'm making sure there's a car object for every body segment, then drawing the wagons from the tail forward and the locomotive last.

Still writing the train's draw code: I'm checking that the body and cars arrays stay the same length as the train grows, then drawing the couplers and wagons.

Still writing the wagon: I'm drawing its shadow, then the wheel pairs on either side, and starting the body.

Still writing the wagon: I'm filling the body with a gradient, adding roof trim, and starting the windows.

Still writing the wagon: I'm adding the windows, lit yellow for passenger cars and dark blue otherwise, outlined with a thin stroke, and drawing a passenger's head in the window when the car has a rider.

Still writing the head drawing: I'm filling the head with a skin-colored circle and starting the hair arc over it.

Still writing the head hair cap and the locomotive's shadow.

Still writing the locomotive: I'm drawing its wheels as dark rounded rectangles on each side, with spokes added on top.

Still writing the locomotive: I'm drawing the cow-catcher at the front, starting its path.

Still writing the locomotive: I'm finishing the cow-catcher's outline and filling the red gradient body, then moving on to the pinstripes.

Still writing the locomotive: I'm adding the pinstripes, then the dark boiler block, and starting the brass dome on top.

Still writing the locomotive's chimney and cab details.

Still writing the headlamp: I'm drawing a soft glow at the front of the locomotive, then a brighter lamp circle over it.

Still writing the locomotive: I'm checking that the chimney and boiler line up with the cab and headlamp, and that the smoke emits from the chimney's forward offset.

I'm moving on to the passengers, which get drawn first so they sit under the train, and I'm adding a small sparks effect on the cell where someone gets picked up. After that comes the HUD and overlay code, and I'm double-checking the demo's pill text and making sure the overlay card doesn't hide too much of the board.

Still writing the status pill: I'm setting its text and style for the demo, play, and derailed states.

I'm setting the status pill's text and style for the demo, play, and derailed states, and the HUD will count the waiting passengers each frame. I'm also thinking about a short toast for demo derailments and a brief overlay message inviting the player to take the wheel.

Now I'm writing the AI routine that picks the train's next direction, starting by marking obstacles and body cells as blocked and recording where the passengers are.

Now I'm setting up the AI driver's direction choice, which blocks off obstacles and body cells and then tests each possible move from the head.

Setting up the AI driver's choice of direction: I'm mapping the blocked cells, then running a flood fill from each candidate move to see how much open space it leaves and how close it gets to the nearest passenger.

Still writing the AI direction choice: I'm scoring each candidate move by how much open space it leaves, how close it gets to a passenger, and whether the tail stays reachable.

Still writing the AI direction choice: I'm scoring each candidate move by open space, distance to the nearest passenger, and whether the tail stays reachable, with a little randomness to break ties.

Still writing the AI direction choice: I'm rejecting moves into the blocked cells, then scoring each remaining one by how close it gets to a passenger and how much open space it keeps.

Still writing the AI direction choice: I'm checking that the chosen move doesn't run into an obstacle or the body, and planning for the demo's AI driver to keep the train moving.

Still writing the rounded-rectangle helper: I'm clamping the corner radius, then tracing the four sides with arcs at each corner.

Still writing the rounded-rectangle helper: I'm checking that a zero corner radius still draws cleanly with arcTo.

Still writing the draw loop: I'm clearing the canvas and working out the frame's transform before drawing the scene.

Still writing the draw loop: I'm applying the screen-shake offset to the background image, then setting the transform so the scene is scaled for the device pixel ratio.

Still writing the draw loop: I'm placing the passengers first so they sit under the train, then the train itself, then the particles and popups on top.

Still writing the d-pad: I'm laying out its grid with a spacer cell, then the up button carrying an inline SVG arrow.

Still writing the d-pad: I'm adding the left and right arrows with their rotations, then the bottom arrow, and filling the empty spacer cells to finish the 3×3 grid.

Still writing the mobile layout: I'm working out the CSS for the directional pad buttons, with rounded corners and an SVG arrow, shown only on narrower screens.

Still writing the CSS: I'm making the big score stat span the full width of the side panel at every size, then checking how the passengers, level, waiting, and best rows and the how-to block stack beneath it. I'm also working through the layout's width limits so the board and side panel fit within the 1280-pixel viewport.

Still writing the layout: I'm checking how the board column sizes at 1024 pixels and at the 900-pixel breakpoint, then confirming the stage fits the 1280×800 viewport.

I'm checking the vertical fit at 1366×768 next: the board width stays at the same 868px column, and the page comes to about 695px tall, so it still clears the viewport without scrolling. At 1920×1080 the 1200px max-width leaves the board small, so I'm considering raising it to 1240px to use the extra room.

I'm settling the max-width at 1240px, since that gives the board more room on a 1920-wide screen without pushing the layout past the viewport. On a 390px-wide phone the frame still works out to a stage about 342px wide, which keeps the cells readable. The side panel comes to roughly 530px of content next to a board of about 585px, so the two columns end up balanced.

Still writing the event handling: I'm making sure a pointer event on the sound button or the d-pad is ignored by the board's tap handler, then looking at the toast's timer.

Still checking the fine details: I'm confirming that the starting spawns use the elapsed time so the pop-in animation begins from zero, and that the first resize runs before any run starts.

Still writing the HTML shell: I'm setting the document's charset and viewport meta tags, then opening the head.

Still writing the HTML head: I'm adding the page styles, with CSS variables for the palette and the card and line colours, and setting the base body font and background gradients.

Still writing the HTML head styles: I'm setting the header's layout and brand block, with the logo and title sized to fit.

Still writing the button and pill styles: I'm sizing the buttons and their text, then giving the live and over states their own teal and rose colours.

Still writing the board frame styles: I'm sizing the frame to its column width, with padding and rounded corners, and checking the layout's horizontal padding so the stage stays inside the viewport.

Still writing the board frame styles: I'm sizing the frame's width from the viewport height, then styling the stage with a 3:2 aspect ratio and a grass-green background, and setting the canvas to fill it.

Still writing the card styles: I'm giving the overlay card its centred text, padding, rounded corners and translucent background, then adding a soft shadow and a backdrop blur.

Still writing the CSS: I'm finishing the toast's text overflow and styling its timer, then checking the card and overlay rules.

Still writing the stat cards: I'm styling the big score tile to span the full row and setting its number to a larger size.

Still writing the stylesheet: I'm finishing the house and board sizing rules, then starting the rule for the d-pad container.

Still writing the dpad styles: I'm laying out the grid with fixed column and row sizes, hiding it by default, and styling each button and its arrow icon.

Still writing the responsive CSS: I'm adding the breakpoint at 900px that stacks the layout into one column and shows the d-pad, then a 420px breakpoint that shrinks the top padding and the score numbers.

Still writing the script: I'm setting up the constants for the grid size and direction vectors, then starting the helper functions.

Still writing the script: I'm defining the colour palettes for the passenger cars, skins and hair, then setting up a shorthand for getting elements by id and a random-number helper.

Still writing the hash helper: I'm mixing the two inputs with integer multiplies and xor-shifts to produce a stable pseudo-random value.

Still writing the helper functions: I'm adding the easing curve, the level-based timing and waiting-passenger limits, and the step speed, then starting a helper that mixes two hex colours.

Still writing the colour helpers: I'm mixing each hex colour toward white or black by a set amount, then building the passenger car object with its light and dark shades.

Still writing the state variables: I'm declaring the canvas size, device pixel ratio, cell size and offsets, and the rest of the game state.

Still writing the state and game variables: I'm setting the canvas offsets, the demo and play states, and the snake's body, cars and passengers.

Still writing the house drawing: I'm defining the function that paints a cottage's shadow and cream walls, with the roof and door to follow.

Still writing the house drawing: I'm adding the roof, a ridge line, and a chimney to finish the cottage.

Still writing the house drawing: I'm laying out the roof's ridge and chimney, then checking how the walls and door show beneath it.

Still writing the house chimney: I'm checking where the roof edge meets the walls so the door stays visible beneath it, and placing the chimney at the top right so it pokes out above the roofline.

Still writing the passenger drawing: I'm working out how each passenger pops in with an overshoot curve over its first half-second, then adding a small bob to its position.

Still writing the passenger drawing: I'm adding a soft white glow pad beneath the passenger, scaled by its pop-in progress, and saving the canvas state before the next transform.

Still writing the passenger body: I'm adding the suitcase, the legs, and starting the torso's rounded shape in the passenger's colour.

Still writing the passenger body: I'm sketching the waving arm and the head with its hair, then starting the timer bar above the passenger's head.

Still writing the passenger's timer bar: I'm placing it above the head, colouring it by how much time is left, and blinking it when it runs low.

Still writing the passenger's arm: I'm drawing it as a rounded stroke from the shoulder, with a small wave that moves it slightly as the passenger animates.

Still writing the passenger drawing: I'm laying out the particle loop and setting each particle's opacity from how far through its life it is, with smoke a little fainter.

Still writing the popup code: I'm setting a bold 14px font for the score labels that float up off the snake's position.

Still writing the popup code: I'm finishing the font, centring the text, and looping over the popups to fade each one and float it upward while stroking and filling its label.

Still writing the update loop: I'm stepping the particles forward by their velocity and damping them, dropping any that have expired, and aging the popups until they're removed.

Still wiring up the loop: I'm finishing the smoke and spark emission, then moving on to the draw and update orchestration.

Still writing the HUD helpers: I'm adding a setter that only touches the text when the value has changed, then starting the function that refreshes the score, passenger and level readouts.

Still writing the event handlers: I'm wiring up the keyboard and pointer listeners, then setting up the toast message helper.

Still wiring up the input: I'm adding a pointerdown listener on the stage that records where the touch or click started, so a later release can be read as a swipe.

Still wiring up the input: I'm finishing the pointerup handler so a swipe longer than about 22px picks the dominant axis and turns the train, and clearing the swipe state on pointercancel.

Now I'm wiring the keyboard: arrow keys and WASD map to the four directions, and M toggles sound.

Next I'm handling the M key: it toggles sound, and I'm leaning toward having it start the game too, so any key press begins play.

Still writing the input handlers: I'm adding the d-pad buttons and the sound toggle, then starting the function that decides how a press or key should be handled while the game runs.

Still writing the input handler: I'm finishing the move-or-start logic so that a press either steers the train or begins the run, and queuing the chosen direction.

Still wiring the game loop: I'm finishing the crash handling so a lost run locks input for half a second, and checking that a start from the game-over state resets cleanly.

Still writing the startup: I'm wiring the resize observer to the stage, starting the demo run, and kicking off the animation frame loop.

Still writing the startup: I'm checking that the resize helper is safe to call before the world exists, and that the background build can read the stage's width and height.

I'm checking how the demo run is handled, and whether the smoke only comes out while the train is still moving.

Still writing the board helper: I'm making sure the cars array stays in step with the body once a passenger is picked up, and then pushing the score popup.

Still writing the particle helper: I'm spawning sparks in a random outward spread, each with its own speed, lifetime and colour.

Still writing the particle helper: I'm adding the explosion burst at a grid cell's centre, spawning a ring of particles with random angles and speeds.