Pressing Play puts you in a public room on a sunlit seaside circuit with a full grid of eight karts: bots drive the karts nobody has, and anyone who arrives takes one over mid-race. Its page says you hold a drift through corners to charge a boost, pick up items from boxes to use on rival karts, and race two laps for points before the next grid lines up. A big-screen mode shows the race on a TV, with phones as the controllers. Its page says it also plays on phones, which we haven't tried.
How the creator made it
The creator says one prompt to Claude Opus 5 started the Three.js racer, which generates its meshes, textures and sound in code. They used the Gauntlet Loop, with agents building separate systems against a shared art guide and other agents scoring screenshots from a running build. The project's write-up says those reviewers missed play problems such as inverted steering and a phone crash, which surfaced when the creator played. The creator later used Opus 5.5 to add online multiplayer.
From their post on X ↗, 2 other posts on X (1 ↗ 2 ↗), a page on GitHub ↗ and a page on ryancampbell.com ↗.
The prompt
I want you to build a kat racing game at the level of the most recent Mario Kart games. It should be utterly perfect, visually beautiful, with every single thing done at AAA quality—from textures to physics to anything you could think of.
Fan out sub-agents and have sub-agents tackle each one individually so that the game is utterly perfect. You should /loop on each item and have a separate sub-agent check it visually to ensure it looks triple A. That separate sub-agent should be a really harsh critic, and if it doesn't look triple A, it should keep going.
Don't stop until each sub-agent is utterly wowed with the quality when compared with the actual Mario Kart game. It should literally compare them side by side blind and say which one looks better. Do this in ThreeJS. /loop until it's utterly perfect. Fan out sub-agents and ultracode.More like this
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The game and its prompt belong to @Ryancampbell. Characters and brands it borrows belong to their owners. Image captured by us. Made this game? Here's how we list it.