Epic VP says AI code tools have stomped out decade-old 'non-deterministic cooking bugs' in Unreal Engine

Epic Games has confirmed that artificial intelligence is now actively shaping the development of Unreal Engine, marking a shift toward an AI-first approach. Marcus Wassmer, Executive Vice President of Development at Epic, stated that AI tools are being used to write and refine code for Unreal Engine, including features and updates. The integration of AI is part of a broader strategy to modernize the engine, which has grown increasingly complex over its lifespan. Wassmer emphasized that AI is not replacing engineers but is being used to streamline processes and improve efficiency.

Wassmer specifically highlighted that AI tools such as Claude and Codex have successfully eliminated "non-deterministic cooking bugs" that Epic had struggled to resolve for over a decade. These bugs, which cause unpredictable behavior in the engine, have been a persistent challenge. Additionally, AI is being used to monitor PC stability in Fortnite, automatically detecting problematic driver and hardware combinations that would otherwise require manual intervention.

The use of AI extends beyond bug fixes, as Wassmer noted that it is helping to modernize and stabilize the engine by trimming unnecessary code and improving overall performance. This approach is being applied not only to Unreal Engine but also to other projects, including the Epic Games Launcher, which was rebuilt using "vibe coding" and now operates faster. Engineers retain control over the scope and direction of AI-assisted development, ensuring it aligns with Epic's goals.

Despite industry concerns about generative AI, Wassmer expressed confidence in its benefits, stating that Epic prioritizes moving quickly over skepticism. He argued that AI-driven development will soon become standard, as it enables faster responses to customer feedback and produces higher-quality software. Wassmer concluded that the best way to address skepticism is through the delivery of superior games and tools, reinforcing Epic's commitment to AI integration.