Rail Rush

Cinevva's analyzer read this game's design doc and its source, then wrote the brief below. "Make your own" hands it to the game creator as your opening message, so you start from a real spec rather than a one-line idea.

Create a 3D endless runner called "Rail Rush" in a bright, stylized low-poly railway/subway environment. Use a third-person chase camera behind and slightly above the runner: perspective camera around 62 degrees FOV, positioned near (player x * 0.2, 4, 9.5), looking toward the track ahead around y=1.15 and z=-14. The camera should follow the runner smoothly while the runner stays near the foreground at z=5. Use a sky-blue background with matching distance fog, soft shadows, bright ambient hemisphere lighting, and warm directional sunlight.

The playfield is three lanes, centered at x=-2.2, 0, and 2.2. Build a long railway with four parallel metal rails at x=-4.4, -1.05, 1.05, and 4.4, brown transverse wooden sleepers spaced along the track, and a wide dark-green ground plane surrounding it. Place a colorful simple city skyline on both sides in the distance: blocky red, blue, yellow, green, and purple buildings with dark roof slabs. Include repeating subway-station scenery along the route: platforms at both sides of the tracks, canopy roofs, support posts, orange benches, overhead signs reading "NEXT STOP RAIL RUSH", and warm light strips. Also include a few roadside advertising panels on poles reading "RUN" in bright colors; these panels gently rotate and sway as they pass. Do not add actual tunnel geometry: the source has tunnel-section hooks but the tunnel creation function is empty, so the visible route remains open.

The player is a stylized block-and-primitive human runner, standing on the central track in the foreground. Model a blue hoodie torso, orange-brown vest panel, peach spherical head, brown hair, red-orange cap with brim, blue cylindrical arms and hands, dark blue pants, cream shoes, and small bright green laces. Keep the character approximately 2.4 units tall and cast shadows. The runner can move among the three lanes with smooth horizontal interpolation, but cannot leave the three lanes. Keyboard controls: A or Left Arrow moves one lane left, D or Right Arrow moves one lane right, and Space or Up Arrow jumps. Jumping applies upward velocity about 8.5, with gravity about 22, and only works while grounded; the player must land before jumping again. Provide equivalent touch controls at the bottom center: left arrow button, a central button labeled "JUMP", and right arrow button.

Make this an endless forward-running game where the world objects move toward the camera/player while the runner remains near the front. Start with a run speed of about 16, gradually accelerate over time, and increase the distance meter continuously. Spawn obstacles ahead around z=-55 at random intervals. Each obstacle randomly selects one of the three lanes. About 30% of obstacles are trains, loaded as a stylized locomotive model; the rest are warning traffic signal props. Trains are wider/taller collision hazards, while signals are smaller. Move obstacles toward the player at the current speed; remove them after they pass the foreground. A collision occurs when the obstacle is close in z, overlaps the runner's lane horizontally, and the runner is not high enough to clear it. End the run immediately on collision.

Also spawn collectible coin lines ahead at random intervals in a randomly selected lane. Each line contains 2 to 4 gold torus-shaped coins, alternating vertically around y=1.25 and y=2.15 and staggered along z. Coins rotate visibly and are collected when the runner is close in x, y, and z. Collected coins increment a coin counter; missed coins disappear after passing the player. Continuously recycle station and advertising scenery farther down the route to create the endless effect.

Overlay a fixed dark translucent HUD over the 3D scene. At top left, show a dark glass panel with the uppercase title "RAIL RUSH" in pale yellow and the instruction text "A/D or ◀ ▶ to change lanes · Space to jump". At top right, show the distance as a large yellow value such as "0 m" and beneath it a cyan coin count such as "◆ 0". During play, update distance as whole meters and display the best distance alongside it, e.g. "123 m · BEST 200"; persist the best distance locally between runs. At the bottom center show the three touch buttons. Before gameplay, show a centered dark translucent modal card with the large title "Rail Rush", text "Stay on the tracks, dodge signals and trains, and see how far you can run.", and a prominent orange/yellow "START RUN" button. Hide this card when starting. On collision, show a centered "Run Over" card reporting the reached meters, collected coins, and best run, with an orange "RUN AGAIN" button. Enter should also restart when not running. Style the UI with rounded dark panels, subtle pale borders, blur/shadow, and a warm orange start button. Make it responsive for desktop and mobile portrait screens, preserving the bottom touch controls and full-screen canvas.