Epic confirms it uses AI tools to code Unreal Engine 6 and Fortnite

Epic executive VP of development Marcus Wassmer confirmed the company uses AI tools to develop code for Unreal Engine 6, Fortnite and UEFN, with engineers guiding the tools rather than writing most of the code. He cited Claude Code and Codex, saying AI nearly eliminated a decade-old non-deterministic cooking bug, sped up shader compression to shrink patches, and cut an estimated three-to-six-week D3D12 rendering layer rewrite to about one week. Tim Sweeney had criticized Steam's AI disclosure requirements, while Wassmer said Epic worries more about moving too slowly than about AI skepticism.