Andrej Karpathy uses Opus 5 to generate 5,500 lines of code for a 3D 'Lord of the Rings' world

According to Beating Monitor, Andrej Karpathy gave Opus 5 the opening passage of The Lord of the Rings, with a budget of 1 million tokens—approximately $10—to create a 3D world using Three.js. The model ran for about two hours and generated 5,500 lines of code, requiring it to position various polygonal assets in 3D coordinates and then write code to animate the entire scene. The result was somewhat rough, but it successfully transformed the text into a playable 3D environment. In the past, few were willing to create such content specifically, as the cost and time investment were not worthwhile. However, LLMs can continue producing this indefinitely, turning highly customized worlds into easily generated content. Karpathy envisions a future where users can enter these dynamically generated worlds as characters, observers, or NPCs—like an on-demand GTA. The project also reveals current limitations of LLMs: Opus 5 cannot efficiently or natively view videos or interact with games, and can only slowly capture screenshots at various checkpoints. Errors occurred frequently during the process, resulting in numerous rough and faulty elements. While it can already build a world, it still cannot smoothly inspect or experience the world it has created.