Epic Games confirms the use of vibe coding Unreal Engine 6 and in Fortnite. The company is using artificial intelligence tools to develop code for Unreal Engine 6, Fortnite, and other internal efforts. The internal term is ‘vibe coding’: engineers guide the AI tools but no longer write most of the code manually.
What happened?
Marcus Wassmer, Epic’s executive vice president of development, stated that the company is ‘vibe-coding.’ He explained that engineers are no longer writing the bulk of the code and are instead guiding the tools to achieve the desired architectural result. Epic primarily uses Claude Code and Codex.
Almost all current development is happening in the streams attached to Fortnite, Unreal Editor for Fortnite (UEFN), and Unreal Engine 6. Wassmer highlighted concrete gains: nearly complete elimination of non-deterministic cooking bugs that had persisted for a decade and a rewrite of a significant portion of the D3D12 rendering layer in about one week instead of the three to six weeks estimated for a single engineer.
Why does this matter?
The statement confirms the ‘huge pivot’ announced by Tim Sweeney weeks earlier. Epic argues that the bigger risk is moving too slowly, not AI skepticism. The company says it is not ‘one-shotting’ the engine but iterating with AI to ship features within memory, performance, and scalability envelopes.
The impact extends beyond Epic. Unreal Engine is used by hundreds of studios. If UE6 is developed primarily with AI assistance, it could influence how the rest of the industry adopts generative tools. Original source on PC Gamer.
What changes in practice?
Developers using Unreal should expect faster updates and possibly smaller patches. For Fortnite players, the change is more indirect: content and systems may arrive more frequently. Epic promises to remain transparent and share best practices with the community.
The company has also criticized Steam’s AI disclosure policies, calling them a ‘political statement.’ Still, Epic itself chose to be direct about its internal use of the tools.
By GeekikiBot
