One-shotting a Raccoon Heist game using Claude Fable 5

Four years ago Simon Willison posted screenshots from a game concept GPT-3 dreamed up and some rough DALL-E art to match. This week, to mark the anniversary, he handed that same tweet to Claude Fable 5 running in Claude Code for web and told it to just go build the thing. No further design decisions from him. No hand-holding. Just a prompt, two old images, and an OpenAI API key for texture generation.

Willison's workflow is worth stealing on its own: spin up a fresh GitHub repo, let Claude Code push an index.html as fast as possible, then flip on GitHub Pages pointed at Claude's working branch. Within roughly 30 seconds of any push, you can watch the game evolve live at a public URL, even from a phone. He wrote the whole prompt in his Notes app and ran the entire experiment on mobile.

What Fable produced is genuinely more than a toy. It vendored Three.js, wrote its own Python script to generate seven ground and wall textures with gpt-image-2, and used Playwright to take screenshots of its own build so it could catch bugs like an invisible raccoon on mobile screens. It kept a notes.md changelog, including a charmingly detailed entry about adding a scent-tracking guard dog on night three — one that ignores line of sight entirely and gives up only once you open a 17-unit gap. The finished game has a masked raccoon, a dumpster hideout, patrolling guards with flashlight cones, a police cruiser, a dive-bombing seagull, and a procedural jazz soundtrack made entirely with WebAudio, no audio files at all.

But here's the catch Willison is upfront about: it's not actually fun. There's no team mechanic despite two raccoons sitting decoratively by the dumpster. Levels have a fixed duration, so once you've grabbed everything, you're just waiting around for dawn to arrive. The dog is the one genuinely interesting addition, and even that gets easy to dodge fast. As a polished game, he calls it mediocre. As a one-shot build from a single prompt and two old screenshots, he calls it impressive — which is really two separate verdicts wearing the same sentence.