Unreal Engine 5.9 MegaJam Preview adds Web platform and AI tools
Epic Games has released the Unreal Engine 5.9 MegaJam Preview, which brings back Web as a target platform and expands AI-assisted workflows. Epic says it is the first engine release built primarily with agentic workflows.
Digital Developer Desk, 6h ago, 2 min read
Epic Games has put out the Unreal Engine 5.9 MegaJam Preview, according to 80 Level. The Preview reintroduces the Web as a target platform, so projects can run in browsers through WebAssembly and WebGPU. Epic built the new web platform code starting from the retired HTML5 platform in UE4.
The release is aimed at the 2026 Epic AI MegaJam, which runs from November 12 to 15. Unreal Engine 5.8 was originally meant to be the last major release before Unreal Engine 6. The team had already been collecting rendering and animation improvements for a possible 5.9 release next year, then changed plans about a week ago to ship this Preview in time for the jam.
Epic describes this as the first engine release built primarily with agentic workflows. A handful of people directed fleets of agents to port the AI tooling from the UE6 development branch and to implement Web as a target platform. Engineers directed, reviewed and tested the agent-written web code. Epic says the approach should let it deliver more UE5 releases with faster bug fixes and work on targeted features, without pulling focus from UE6.
On the feature side, the Preview includes major improvements to Python scripting and AI-assisted workflows, including Unreal MCP, Unreal Assistant and Unreal Canvas, Epic's AI-powered content creation tool. It also brings animation, rendering and world-building updates, such as Lumen World Cache and better Nanite culling.
The Preview was assembled in roughly a week and had a shorter QA period than usual. Epic says it is still cleaning up some of the agent-written code, and that parts of the web renderer are prototypes it plans to refactor before the full 5.9 release ships. As with all Preview releases, it is under active development and may be unstable.
You can try it during the Epic AI MegaJam, or test it with a copy of your own project and report bugs. Download it through the Epic Games Launcher.
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