Epic Games Confirms Vibe Coding for Unreal Engine 6 and Fortnite Using AI Tools

Epic Games Embraces AI-First Approach for Major Projects

Epic Games has officially confirmed that AI coding assistants now drive development for Unreal Engine 6, Fortnite, and other internal projects. In a statement to This Week In Video Games, Marcus Wassmer, Epic's executive VP of development, explained the company's shift toward what they call vibe coding1

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. Engineers no longer write the bulk of code manually but instead guide AI tools to achieve desired architectural results while maintaining memory, performance, and scalability standards2

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Claude Code and OpenAI Codex Accelerate Development

Epic Games relies primarily on Claude Code and OpenAI Codex for its AI-driven development workflow. Wassmer highlighted specific achievements, noting that these AI tools to code Unreal Engine 6 helped rewrite a significant portion of the D3D12 rendering layer in approximately one week—work that would typically require three to six weeks for a single engineer3

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. The company also credits AI coding assistants with nearly eliminating non-deterministic cooking bugs that plagued development for a decade and accelerating shader compression work, which reduces patch sizes2

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Speed Over Skepticism in AI Integration

Wassmer emphasized that Epic Games prioritizes rapid adoption over caution when implementing generative AI. "We are more concerned about the risks of moving too slowly than we are about AI skepticism," he stated1

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. This AI-first approach marks a dramatic reversal from Tim Sweeney's position just one year ago, when the Epic CEO denied using AI for Unreal Engine updates1

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. Almost all current development occurs in dev streams attached to Fortnite, Unreal Editor for Fortnite, and Unreal Engine 62

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Epic Games Store Launcher Showcases Mixed Results

Earlier this month, Epic Games revealed it had vibe-coded a new version of the Epic Games Store launcher, claiming it was "way faster and more responsive" than the current version1

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. However, the launch encountered problems. Social media quickly filled with clips showing the launcher hallucinating, and one user claimed the new launcher bricked their PC1

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. While Epic initially claimed the launcher booted faster than Steam, Valve subsequently released a store update that eliminated the performance advantage1

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Developer Community Responds with Concern

The AI integration in game development has sparked significant debate among developers. Many express alarm that Unreal Engine 6, one of the most-used video game engines, is being vibe-coded by AI, raising concerns that Epic may not fully understand all the code they ship1

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. Some developers question why they should pay Epic's licensing fees if they could vibe-code their own engines instead1

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. Developer skepticism centers on maintainability, job security, and whether engineers will truly comprehend the code they deliver3

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Tim Sweeney Defends AI Development Practices

Tim Sweeney has become increasingly vocal in supporting generative AI, predicting a "golden age of gaming" enabled by the technology1

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. He confirmed on Sunday that Epic uses AI tools to develop code for Unreal Engine1

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. Sweeney has repeatedly criticized Steam's AI disclosure requirements, calling them a "political act" that "confiscates opportunity" from developers and forces them "to write a political statement to be used against them by the hate mob"2

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Future Projects Adopt Full AI Workflows

Epic recently delayed an unannounced game featuring Marvel and Star Wars character crossovers as the company transitions to its AI-first development approach. "No more handwritten code," one director reportedly told staff1

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. All art for the game will reportedly be generated with full AI workflows1

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. Wassmer argues that taking a halfway approach to AI in development isn't viable and that transparency about their methods combined with quality results will counter skepticism2

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