Beat 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 browser-playable 3D rhythm endless-style runner titled “Beat Sprint.” Use Three.js for the scene and Tone.js (or equivalent browser synths) for a generated electronic soundtrack. The camera is a fixed third-person perspective looking down a centered neon sci-fi track: dark navy space-like background with fog, scattered cyan/pink/white stars, a broad dark rectangular road extending into the distance, glowing cyan center stripes, and bright purple rails along both edges. Add a large cyan horizon halo in the distance and pulsing translucent beat rings near the player. The player is a small centered futuristic runner made from a glowing white/cyan capsule body with a cyan visor and a dark circular shadow on the track; the player stays at the front of the track and jumps vertically rather than changing lanes. The track and beat markers should scroll toward the camera to convey forward motion, while obstacles travel from far ahead toward the player.

On the start screen, show a full-screen dark translucent overlay and centered rounded dark panel. Include the small uppercase label “RHYTHM RUNNER,” the large title “Beat Sprint,” explanatory text saying to run the line and jump on the beat, a prominent blue-to-purple pill button labeled “START RUN,” and four small tip cards: “Space / ↑ / tap to jump,” “Perfect jumps clear the tall bars,” “Miss a bar and you lose life,” and “Mobile works with the jump button.” During play, keep a translucent rounded HUD panel across the top with SCORE on the left, STREAK in the center, and LIFE on the right, initially 0, x0, and 3. Near the bottom, show a horizontal cyan-to-pink timing/progress bar and a large circular gradient “JUMP” button at the lower right. Show brief centered feedback pills such as “Feel the beat,” “Perfect jump,” “Good jump,” “Off beat,” “Clean clear,” “Cleared,” and “Missed bar,” color-coded gold/cyan/pink/red.

Core interaction: clicking Start, pressing Space or Up Arrow, tapping the canvas, or using the Jump button starts the run if it has not begun; afterward those actions trigger a jump if the player is grounded. The music is 124 BPM, with kick on quarter notes and synth bass, snare, hi-hat, and triangle lead patterns on sixteenth notes. Run a 24-bar phrase with four beats per bar. Schedule tall glowing hot-pink rectangular bars in the center lane on a repeating beat pattern [true,false,true,false,true,true,false,true], after an initial lead-in of four beats. They spawn far down the track and move toward the player at high speed, reaching the player on their scheduled beat. The player must be above a high threshold (roughly y 2.45 versus grounded y 1.15) when a bar reaches the player to clear it; otherwise lose one of three lives and reset the streak. Remove passed obstacles after they move behind the camera.

Timing mechanic: calculate the nearest beat from the music clock. A jump within 0.09 seconds of a beat is PERFECT: give a strong/high jump velocity around 11.4, add 120 points plus 8 per existing streak, increment the streak, and display “Perfect jump.” A jump within 0.18 seconds is GOOD: use velocity around 9.6, add 70 plus 4 per streak, increment streak, and show “Good jump.” A later/off-beat jump uses velocity around 7.8, awards only 10 points, resets streak, and shows “Off beat.” Apply gravity around -25 so the capsule rises and lands automatically at y 1.15. Clearing a bar awards 45 plus 5 per streak, with stronger “Clean clear” feedback if the last jump was perfect. When lives reach zero, stop the run and music and show the overlay again with text like “Run over — score [score]. Hit retry and stay closer to the beat for stronger jumps.” and a “RUN AGAIN” button. If the player survives the entire 24-bar phrase, add a life-based completion bonus (120 per remaining life) and end the run.

Make the neon materials emissive and polished: cyan road accents, purple rails, pink obstacle bars, a white/cyan player, reflective dark road, subtle bloom-like glow through emissive materials, and beat-responsive rings/markers. Animate the timing bar and rings with the beat phase, flash the track briefly on a missed bar, pulse marker brightness on each beat, animate the runner’s tilt and emissive intensity according to jump grade, and gently follow the runner’s vertical motion with the camera. Ensure responsive resizing and mobile touch controls; use a dark, high-contrast, rounded glass-panel UI matching the supplied visual style.