Build a 3D kart racing game (fixed spec)

the prompt

Build a complete, playable 3D kart racing game in the browser. The spec below is fixed — every frontier model in this comparison receives this identical prompt, and the builds get played side by side. Context you should know: this is going into a video watched by a large audience, your build will be played on camera against two other frontier models, and your work will be credited to you by name. The audience is judging how it looks and how it feels to drive, in about sixty seconds of screen time. Go all out. Requirements: 1. **One original track, designed — not generated.** A closed circuit with real character: elevation change, at least one long sweeping corner and one tight technical section, a hazard or shortcut that rewards a risk, and readable sightlines so a first-time driver knows where the track goes. Three laps. It should be a track someone would want to learn, not a loop of gray ribbon. 2. **Drift is the core mechanic and it has to feel right.** Hold to drift, charge a boost through the turn, release for a speed burst with a tiered payoff for holding it longer. The handling model needs weight — grip that breaks progressively, a slide the player can control with counter-steer, and a chassis that reacts to the surface. Arcade, not simulation, but with honest physics under it. If the drift doesn't feel good, nothing else in the build matters. 3. **Five AI opponents that actually race.** They follow real racing lines — outside-inside-outside through corners, braking points, an attempt at the shortcut. They collide with the player and each other, recover from spins, and stay close enough to make the race tense without teleporting. Mild rubber-banding is fine; obvious cheating is not. 4. **At least three usable items**, picked up from the track. One offensive, one defensive, one speed. They need a visible pickup, a clear activation, and impact the player can see and hear. 5. **HUD and race structure.** Lap counter, position, speedometer, lap and total time, item slot, minimap or track position indicator. A three-two-one countdown at the start, a finish sequence, and a results screen with placings and times. One line of on-screen control instructions. 6. **The graphics bar is high.** This should look like a game someone would ship. Real materials and lighting, shadows, a coherent art direction carried through the kart, the track, and the environment. Motion effects that sell speed: camera FOV punch on boost, drift sparks that tier with the charge, tire marks, dust and impact particles, screen shake on collision. Untextured primitives and programmer art are failures regardless of how good the driving is. No neon-on-black — it reads as a default and has been seen too many times. 7. **Sixty locked frames per second with all six karts, all particles, and the full track on screen.** Frame drops during a race are the most visible failure mode on camera. Profile it and fix it. 8. **Audio, synthesized via the Web Audio API.** Engine note that tracks throttle and speed, drift and boost, impacts, item sounds, countdown. No hotlinked audio files. 9. **Single self-contained `index.html`.** Any library via CDN — three.js, a physics engine, anything you want. No build step, no server, no API keys, no hotlinked sprites or textures. Generate art procedurally, author it in canvas/SVG/WebGL, or use library-driven generation. You have free reign to look up what libraries exist and how to use them. 10. **Keyboard controls**, explained on screen in one line. Playable the moment it loads — no menu maze, no tutorial wall. 11. **QA it by actually playing it.** Race several full three-lap runs. Confirm the drift charges and pays off, the AI completes laps without getting stuck or cutting the track, collisions are honest, items work, lap counting is correct, nothing softlocks, and the frame rate holds through a full pack fight. Fix what breaks. Work completely autonomously. Do not ask for anything until it's finished. DONE when: a first-time driver can load it and enjoy driving it within ten seconds, the drift feels good, six karts race a clean three laps at sixty frames per second, and it looks like a shipped game.

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