Epic Games has released the Unreal Engine 5.9 MegaJam Preview, which it described as "the first Unreal Engine release built primarily with agentic workflows."
According to the announcement on Epic's developer forums, the preview came together in about a week. "A handful of people directed fleets of agents to port the AI tooling from our UE6 development branch and implement Web as a target platform," Epic wrote. The AI agents wrote the code for the new web platform, starting from the HTML5 platform that Epic retired with Unreal Engine 4, while engineers directed, reviewed and tested the work.
Epic was open about the trade-offs. The build had a shorter QA pass than usual, some agent-written code is still being cleaned up, and parts of the web renderer are prototypes that will be refactored before the full 5.9 release. The company said the approach lets it ship more UE5 updates and faster bug fixes "without pulling focus from UE6," and that agents will help it triage bug reports during the preview period.
What's in the preview
Most of the new features are experimental and aimed at AI-assisted development. Unreal MCP, the engine's connection point for AI tools (MCP stands for Model Context Protocol), now launches with the editor and lets agents handle rendering, source control, profiling, debugging, gameplay testing and level creation. A new Fab toolset lets agents search Epic's asset store and install free or purchased assets straight into a project.
A new in-editor panel, Unreal Assistant, lets developers work with coding agents such as Claude Code, Codex, Cursor or OpenCode inside Unreal Editor. Unreal Canvas, available in the editor and as a web app, generates concept art, images, 3D meshes and video from prompts, reference images or a developer's own scenes, using AI models that developers connect with their own API keys. Projects can also now run in a web browser, though only experimentally.
The preview was timed for the 2026 Epic AI MegaJam, which runs from November 12th to 15th. Teams of up to five people can use as many AI agents as they like to build a game in Unreal Engine or Unreal Editor for Fortnite (UEFN), with standout entries eligible for grants of up to $50,000. The release follows Epic's recent confirmation that Unreal Engine 6 will drop Blueprints and Actors.
