Epic Games is no longer hedging about how much AI is in its tools. “Yes, we are vibe-coding things,” Epic’s executive vice president of development Marcus Wassmer said in a statement to This Week in Videogames, quoted by PC Gamer. “That means our engineers are no longer writing the bulk of the code, but they are still guiding the tools to get the architectural result we want.”
Wassmer said almost all current development is happening in the streams tied to Fortnite, Unreal Editor for Fortnite and Unreal Engine 6. He named Claude Code and Codex among the tools in use, and said the team is “iterating with AI” rather than “one-shotting” the engine, while keeping it within memory, performance and scalability targets.
He listed several wins. Epic says AI helped almost completely eliminate non-deterministic cooking bugs it had been fighting for a decade, and sped up work on shader compression that significantly reduces patch sizes. A rewrite of a large part of the D3D12 rendering layer, which Wassmer estimated would take one engineer three to six weeks, was done in about a week. Fortnite is also getting automated stability monitoring that can identify the root cause of crashes and generate fixes.
Wassmer also addressed critics directly, as Rock Paper Shotgun reported. “We are more concerned about the risks of moving too slowly than we are about AI skepticism,” he said. “We don’t think it’s viable to take a halfway approach to AI in development.” He argued the best answer to skeptics is the quality of the games and tools Epic ships.
Tim Sweeney confirmed the approach on X, writing that Epic is now using AI tools to develop code for Unreal Engine. Sweeney has also criticized Steam’s AI disclosure labels this month, calling them “just as partisan as mandatory political essays.”
The comments cap a busy few weeks of AI news from Epic. The company walked back an AI requirement for its Unreal AI MegaJam after pushback, and Sweeney said this week that Epic is removing its ban on AI training from Unreal Engine and MetaHuman outputs. Unreal Engine 6 does not have a public release date yet.
