Agentic Coding Demo
Karpathy turns a Lord of the Rings paragraph into a playable Three.js world with Opus 5
Karpathy handed Opus 5 a ~1M-token / ~$10 budget with the opening of The Lord of the Rings, and the model spent roughly two hours writing 5,500+ lines of Three.js to procedurally render and animate the story, self-correcting via screenshots. A playable browser version was published, spotlighting long-horizon agentic creative coding.

