Wassmer named Claude Code and Codex as tools in use, and credited them with concrete results: the near-elimination of non-deterministic cooking bugs Epic had fought for a decade, faster shader-compression work that cuts patch sizes, and a rewrite of a significant portion of the D3D12 rendering layer. He estimated that rewrite at three to six weeks for one engineer; it was completed in about a week, he says, with lower CPU time and fewer bugs.

The confirmation is not entirely new. In a June Unreal Engine 6 blog post, Wassmer wrote that Epic had opened up broad AI code-generation usage across its engineering teams, and Epic previously claimed it had vibe-coded the Epic Games Launcher to be faster than competitors. A mid-October Eurogamer report likewise noted Epic's new "vibe-coded" Epic Games Store, which is also coming to Linux.

Wassmer argued there is no halfway option: Epic wants to be upfront about its AI use, share best practices with other developers, and build the best UE6 it can. "We are more concerned about the risks of moving too slowly than we are about AI skepticism," he said. The stance sits oddly alongside Sweeney's criticism this week of Steam's AI disclosure requirements, which he called, in effect, forced political statements.