Karpathy Tests Opus: Generates 3D World with 5,500 Lines of Code for $10

机器之心 · wechat · 2026-08-03

Andrej Karpathy recently challenged an LLM by providing it with the opening text of The Lord of the Rings and a budget of about 1 million tokens (approx. $10) to generate an interactive 3D scene using Three.js.

The model autonomously spent nearly two hours writing around 5,500 lines of code. It understood the plot, created polygonal assets, placed them in a 3D coordinate system, and orchestrated camera movements and animations. Although the final visual result was somewhat rough, the experiment demonstrated LLMs' potential to build complex virtual worlds from scratch. Karpathy envisioned this as a future on-demand, transient "personalized GTA."

The experiment also exposed a key limitation of current models: the lack of native video perception. The model struggled to efficiently "see" its own output, relying on slow screenshots of static images to make adjustments, leading to minor clipping and misalignments.

Related event: Karpathy's LOTR Benchmark: LLM Writes 5500 Lines of Code to Build 3D World(7 posts)→

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