Kart Royale

Kart Royale

A Mario Kart-style racer in the browser. No art assets. No Blender, no Unity,
no textures, no models, no fonts, no audio files — every mesh, texture, sound and
note is generated in code at load time.

Play: racing.ryancampbell.com ·
Write-up: ryancampbell.com/kart-royale

*Every pixel above is generated at runtime. The kerb stripes, the crowd, the tyre
tread, the sparks, the sky — there is not a single image file in this repository.*

Built by Claude Opus 5 from a single prompt, then improved over nine orchestrated
multi-agent rounds.

The prompting technique is the Gauntlet Loop,
named and developed by Matt Shumer: give a lead agent a goal and a
concrete example of what great looks like, let it decompose the work into pieces that can be
improved independently, and give each piece a *separate* critic that compares the output against
the bar and sends it back until it clears. The separation of builder and critic is the whole
idea — a builder grading its own homework is not a measurement.

The interesting wrinkle in this project was what happened when the bar could not be used as
stated. See below.

The prompt

Verbatim, typo and all:
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…