Shape Sprint

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 mobile-friendly 3D arcade racing game titled "Shape Sprint" using a forward-facing third-person chase camera. The player controls a green vehicle racing straight ahead along a three-lane track, with three red AI racers nearby. The race is 420 world units long and begins with a 3-second countdown showing large centered "3", "2", "1", then "GO!". The track runs through a bright stylized outdoor environment: blue sky with light fog, green grass surrounding the track, soft shadows, and evenly spaced small trees on both sides. Use a wide track with three lanes at x positions approximately -3.3, 0, and 3.3, a central dashed white divider, and these sequential surface sections: dark gray road from distance 0–105, bright blue water from 105–190 with a translucent pale aqua/foam layer, dark gray road from 190–290, brown hill/terrain from 290–360, and dark gray road from 360–425. Keep the camera behind and slightly above the player, smoothly following its position and looking ahead down the track; the player should visibly move forward while the world and racers remain in view.

The defining mechanic is gesture-based shape transformation. Let the player draw directly anywhere on the screen with pointer/touch input, render the stroke temporarily as a white line, and recognize a gesture after release when it has at least 3 points and a path length of at least about 55 pixels. Recognize a mostly closed, circular stroke as a circle, a long mostly straight stroke as a line, and a closed/angular stroke with at least two sharp corners as a triangle. A circle changes the player into a green car and sets speed to about 11.5. A triangle changes the player into an orange climbing vehicle (a chunky orange rectangular body with four dark wheels and a yellow angled front blade) and sets speed to about 9.2. A line changes the player to a boat when currently on the water, or to a train when on any other surface, and sets speed to about 13.2. The boat is a simple blue hull with a cream cabin; the train uses a small train-carriage model. Initially and after restarting, show the green race car and speed about 10. Shape selection should replace the visible player model and briefly pulse/enlarge the player.

Allow lane switching by tapping the lower portion of the screen (below roughly 72% of screen height), provided the player is not drawing and the race is running: tapping the left half moves one lane left, and tapping the right half moves one lane right, clamped to the three lanes. Smoothly interpolate the player toward the selected lane. Do not treat taps in the upper area as lane controls. The player advances automatically while the race is running; update the displayed surface based on distance, and finish when reaching 420. The three red AI racers start slightly behind in the three lanes, move automatically with slightly different speeds, subtly change lanes over time, and use rubber-banding. They should transform to a boat over the water segment, back to cars from 190–290, to orange climbers on the hill segment, and back to cars after 360. No combat, weapons, collectibles, or collision requirement is needed; this is a clean race focused on changing shape and choosing lanes.

Build the HUD as a readable canvas overlay over the 3D scene. At the upper left, show a translucent dark panel containing "SHAPE SPRINT", "Mode: [current mode]", and "Surface: [current surface]". Below it, show a full-width thin progress bar with a gray translucent background and yellow fill based on distance across the 420-unit race. Near the bottom center show the most recent gesture text, initially "Draw a shape", then labels such as "CIRCLE → CAR", "LINE → BOAT / TRAIN", or "TRIANGLE → CLIMBER"; below it show the instructions "Draw a circle, line, or triangle anywhere" and "Tap left / right side to switch lanes". During countdown show the large countdown text in the center. When the player reaches the finish, pause the race and overlay a translucent black full-screen panel with large yellow "FINISH!" and white "Tap to race again"; tapping restarts the countdown, resets distance/lane/mode/surface/gesture, resets the AI positions and models, and starts a new race. Use a colorful low-poly/stylized racing-kit aesthetic, bright sky-blue background, green grass, simple geometric custom vehicles, directional sunlight, ambient sky lighting, fog, and soft shadows. Make the layout responsive to portrait mobile screens and support pointer/touch drawing and taps.