One-Shotting a Complete Game Using Claude Fable 5
Simon Willison demonstrated the capabilities of Anthropic's Claude Fable 5 by generating a fully playable game, "Raccoon Heist," from a single tweet prompt containing a 2022 game concept. The model built the entire game autonomously using Claude Code for web. This showcases the rapid advancement of next-generation LLMs in software engineering, moving from simple text completions to generating complete, functional applications from minimal prompts. It highlights how AI agents can streamline game prototyping and development workflows. Willison used GitHub Pages to test the game in real-time by instructing Claude Code to commit an `index.html` file to a repository branch. Claude Fable 5, released in June 2026, is a "Mythos-class" model designed for general use with built-in safety safeguards.
## BACKGROUND
Claude Fable 5 is a powerful large language model developed by Anthropic, released alongside the restricted-access Claude Mythos 5. Claude Code for web is a browser-based tool that allows developers to delegate coding tasks to Claude, running on Anthropic's cloud infrastructure. "One-shot" generation refers to the AI's ability to produce a complete, working output from a single prompt without iterative human corrections.