Trailbound

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 “Trailbound” as a portrait-friendly 3D endless runner in Three.js. Use a bright stylized low-poly outdoor scene: a cyan-blue sky with matching distance fog, a broad flat green grassy ground plane, and a brown three-lane road running straight into the distance. The road is about 7.4 units wide, with two broken pale yellow lane-divider stripe lines, and pine trees placed on both sides of the road at varying distances and sizes. Use simple Kenney-style low-poly nature assets for the pine trees; include a small trail/sign prop off the left side in the distance. Light the scene with soft sky/hemisphere light and warm directional sunlight with shadows.

Place the runner in a third-person follow camera, behind and slightly above the character, looking forward down the road. The camera should be a perspective camera with a mild side-follow effect as the character changes lanes. The player is a simple stylized humanoid made from primitives: a red-orange capsule torso, a peach spherical head, a dark navy rectangular visor on the front of the head, and two short dark legs/shoes. Keep the character centered near the bottom/front of the view and make it subtly bob/animate while running.

The core mechanic is an endless three-lane dodge-and-jump run. The player automatically runs forward while the world and spawned objects move toward the camera; there is no manual forward control. The three lane x positions are left, center, and right. Left/right controls shift the target lane, with smooth damping rather than instant teleporting. Support keyboard Arrow Left/Right and A/D, plus pointer/touch swipes horizontally: swipe left moves one lane left and swipe right one lane right. A tap starts the run from the title screen. Space, Arrow Up, or W makes the character jump, and an upward swipe also jumps. The character has vertical gravity, starts a jump with upward velocity, and lands back on the road.

Continuously spawn obstacles ahead on a random lane, moving toward the player as the run progresses. Most obstacles are low yellow horizontal bars supported by two brown posts; occasionally use a larger wooden gate/fence-gate model. Obstacles occupy one lane. The runner can avoid them by changing lanes or jumping over them. Detect a collision when an obstacle is close in depth and lateral position and the player is still low enough; then end the run. Remove obstacles after they pass the camera. Also spawn glowing gold torus-shaped collectible coins on random lanes ahead of the player. Coins rotate as they approach, and collecting one when close in depth/lateral/vertical space removes it and adds 150 points. Remove missed coins after they pass.

Gradually increase automatic running speed over time, starting around 10.5 and capping around 22. Track distance in meters, with the normal score equal to floor(distance * 10), and add the coin bonus on collection. Save the best score in localStorage under a Trailbound-style best-score key and display it on later runs. The run should be endless with objects recycled/removed as they pass.

Render a canvas HUD over the 3D scene. In the upper-left, show a translucent dark blue-gray rectangular panel with large white “SCORE [number]” and a smaller line “DIST [whole number]m   BEST [number]”. On the initial idle screen, show a centered dark translucent instruction card reading “TRAILBOUND” in large warm pale-yellow text, then “Tap to run  •  swipe or arrows to dodge” and “Jump over barriers with Space or swipe up” in white. Once an obstacle collision occurs, show a centered dark translucent “RUN OVER” card with the score and “Tap to try again”; tapping or pressing Enter should reset obstacles, score, distance, speed, and player state and begin a new run. Keep the presentation clean and arcade-like, with no extra invented weapons, lives, power-ups, enemies, or menus. Ensure the game fills the viewport, supports resize/orientation changes, and maintains the simple colorful low-poly style visible in the reference.