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.

Recreate a 16:9 browser endless runner titled “Rail Rush // First Person.” Use a real-time 3D first-person perspective: the camera is at about eye height (roughly 1.72 units) and moves automatically forward along the negative Z axis, with no visible player body. The player runs on three parallel railway lanes centered at X positions approximately -2.55, 0, and 2.55. Each lane is represented by two long steel rails, wooden sleepers/ties at regular intervals, and a dark gray ballast bed; add wide dark walkways on either side and thin warm yellow lane-divider stripes between the three tracks. The scene should feel like a stylized low-poly industrial rail corridor, with a muted blue-gray sky, atmospheric fog, warm directional late-sun lighting, and dark blue/gray materials with yellow-orange accents.

Core gameplay is an endless forward runner. The player continuously advances, starting at about 19 units/second and gradually accelerating up to about 31 units/second. Track distance increases continuously and is displayed in whole meters. The player can shift one lane at a time between the three lanes, smoothly interpolating toward the selected lane. Support keyboard controls A/D or Left/Right Arrow for lane changes. Support Space, Up Arrow, W, or a visible on-screen JUMP button to jump. Jumping uses an arc with strong gravity: launch vertically, rise above obstacles, then land automatically; another jump is only possible once grounded. The run ends immediately when the player reaches an obstacle in the current lane at close range while not high enough to clear it.

Procedurally place/recycle rows of hazards and collectibles ahead of the player so the course continues indefinitely. Rows are spaced about 18 units apart. A row may contain a large industrial train occupying one lane: a blocky blue-gray train body, red-orange lower/front nose, dark windows, and a front windshield. Trains are tall enough that the player must jump high to clear them (collision threshold around 1.65 units). Rows may instead contain a low construction barrier in one lane, with a red-orange rectangular body and a bright yellow horizontal stripe; jump over it (collision threshold around 1.0 unit). Hazard positions are randomized among the three lanes, and some rows can have no hazard. Add gold ring-shaped coins in occasional lines of five, all in one lane, spaced along the forward direction, with alternating heights around 1.35 and 1.53 units. Coins spin visibly and are collected when the camera/player is near them in the matching lane; collected coins increment the coin count and disappear/recycle.

Dress the sides of the corridor with repeated low-poly industrial/city buildings in dark neutral colors, placed around X=-9.2 and X=9.2, with varied scale and right-angle rotations. Occasionally place a simple dark tunnel structure spanning the corridor: a heavy dark top slab and side columns, with a thin glowing yellow strip near the tunnel ceiling. Recycle obstacles, coins, buildings, and tunnel scenery from behind the camera to far ahead to create an endless route rather than loading a finite level. Keep the forward-facing camera centered on the track direction, smoothly follow horizontal lane movement, and raise the camera during jumps. Use soft fog so distant rails and buildings fade into the blue-gray environment.

Overlay a dark translucent HUD over the 3D scene. At the upper left, show a rounded translucent panel reading “RAIL RUSH // FIRST PERSON” in bold uppercase yellow lettering. At the upper right, show rounded translucent stats with “Distance [whole number] m” and “Coins [number]”. At the bottom center, show the hint “A / D or ← / → to change lanes · Space / ↑ to jump.” At the bottom corners provide touch-friendly controls: left and right rounded arrow buttons grouped at bottom left, and a rounded yellow-accented “JUMP” button at bottom right. Make these controls usable by pointer/touch and slightly subdued on desktop until hovered.

On collision, stop the run and show a centered game-over modal over a dark translucent screen overlay. The modal is a dark navy rounded rectangle with a subtle yellow border, large yellow uppercase heading “RUN ENDED,” the final line formatted like “6 m · 0 coins,” and a large rounded “RUN AGAIN” button. The restart button resets distance and coins, returns the player to the center lane at ground level, hides the modal, and generates a fresh forward course. The visual style should remain clean, minimalist, polished, and arcade-like, with high-contrast yellow UI and accents against dark translucent navy panels.