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 playable 3D endless runner titled "Rail Rush". Use a third-person, slightly elevated perspective behind a stylized runner moving forward automatically along three parallel railway lanes. The scene should have a pale blue sky/background with distance fog, a dark charcoal track bed, three lane positions spaced horizontally, paired metallic rails in each lane, repeating brown wooden sleepers, and dark blue-gray platform/wall structures along both sides. Add simple distant blocky blue-gray city buildings beside the track. Use soft shadows, bright daylight, and a clean low-poly/stylized look.

The player is a simple humanoid assembled from primitive shapes: pink-red rectangular torso and arms, dark navy rectangular legs, a peach spherical head, and a dark cap. Place the runner near the camera at the center lane, facing down the track. The runner continuously advances through the world while obstacles and collectibles move toward the camera. Smoothly interpolate horizontal movement between the three lanes. The game starts on a centered dark translucent rounded modal card; hide it after starting. The initial modal title is "Rail Rush", with Arabic instructional copy meaning run between trains, collect coins, jump over barriers, and use arrows or touch buttons, plus a gold rounded start button labeled "ابدأ الجري". On collision, stop the run and show the modal again with Arabic game-over title "انتهى الجري", score and collected coins, and a replay button labeled "إعادة اللعب".

Core endless-runner rules: begin at speed 16 and gradually increase speed by 0.34 per second, capped at 29. Continuously increase score at speed*2.3 per second, and add 120 points whenever a coin is collected. Persist the best score in local storage and show the integer score, coin count, and best score. Spawn patterns ahead on the track around z=-48: sometimes one obstacle in a random lane (a bright orange construction barrier or an electric subway train), sometimes two obstacles leaving one randomly selected safe lane, and sometimes a line of seven coins in one lane with a possible barrier in an adjacent lane. Spawn coins as flat gold coin sprites, rotating as they approach, generally around character head/chest height with varied heights. Remove passed objects.

Obstacles must be lane-based. Trains should be large subway train models or visually similar tall train cars; barriers should be orange construction barricades with a chunky base and striped/construction detail. Collision checks should use horizontal lane proximity and forward distance. The runner can avoid obstacles by changing lane, jumping, or sliding: left/right changes one lane with keyboard ArrowLeft/ArrowRight or A/D, up/jump uses ArrowUp/W/Space, and down/slide uses ArrowDown/S. Jump from the ground with upward velocity about 8.6 and gravity about 22; low barriers can be cleared while airborne, while trains require a higher jump. Sliding lasts about 0.62 seconds and prevents collision during that period. Also support touch/swipe gestures on the canvas: horizontal swipes change lane and vertical swipes jump or slide. Provide large on-screen controls: left/right arrow buttons at the lower left, and Arabic buttons "قفز" (jump) and "انزلاق" (slide) at the lower right.

The HUD is an HTML/CSS overlay above the canvas, in a dark navy/black translucent glass style with thin light borders, rounded corners, and subtle shadows. Put three top pills in a row: COINS, SCORE, BEST, with the score number highlighted gold; labels are small uppercase English and values are bold. Keep the bottom controls and a centered hint visible: "← → تغيير المسار · ↑ قفز · ↓ انزلاق". Use a dark translucent centered card with rounded corners for start/game-over messaging. Make it responsive and touch-friendly, with no scrolling, and render the 3D scene full-screen behind the HUD.