Epic Games Says AI Helped Fix Decade-Old Unreal Engine Bugs

Epic Games says artificial intelligence coding tools have helped its engineers address technical problems in Unreal Engine that had persisted for nearly a decade, while accelerating work on rendering and software optimization.

Marcus Wassmer, Epic Games' executive vice president of development, discussed the improvements in statements provided to This Week in Videogames, published on October 27, 2026.

According to Game Developer's coverage of the original statements, Epic has been using Claude Code and OpenAI Codex to assist with programming across Unreal Engine, Fortnite, and Unreal Editor for Fortnite.

One reported improvement involves non-deterministic asset-cooking bugs, which can cause inconsistent results when preparing game content for different platforms. Wassmer said the team had almost completely eliminated this particular category of problems.

AI tools also accelerated shader-compression development, potentially reducing the size of future game updates.

Another improvement involved rewriting a substantial portion of Unreal Engine's Direct3D 12 rendering layer. Wassmer estimated that the task would normally require three to six weeks for one engineer, but the team completed it in approximately one week.

Epic reported lower CPU overhead and fewer bugs following that work, although independent performance benchmarks have not been published.

The company is also using AI-assisted monitoring to identify stability problems involving specific PC hardware and graphics drivers.

Wassmer confirmed that engineers continue supervising AI-generated code and refining its architecture rather than relying on fully automated development.

Much of this work is focused on Unreal Engine 6 and Fortnite-related development. Unreal Engine 5.9 remains a possibility rather than a confirmed release.

These improvements do not mean every Unreal Engine performance issue has been resolved.