Epic confirms AI tools are coding Unreal Engine 6 and Fortnite

Epic Games is using AI tools including Claude Code and Codex to develop code for Unreal Engine 6, Fortnite and UEFN. EVP Marcus Wassmer said engineers no longer write most of the code but guide the tools; a D3D12 rendering layer rewrite took about a week instead of 3–6 weeks.

• Claude Code and Codex are used across UE6, Fortnite and UEFN development
• D3D12 rendering layer rewrite took about a week instead of 3–6 weeks
• AI nearly eliminated non-deterministic cooking bugs and sped up shader compression
• Tim Sweeney criticized Steam's mandatory AI disclosure rules