Epic Games has released the Unreal Engine 5.9 MegaJam Preview, the first version of the engine built primarily with agentic workflows. A small team of engineers directed fleets of AI agents to port AI tooling from the UE6 development branch and implement web as a target platform, starting from the retired HTML5 support in UE4.
What happened?
The preview was assembled in roughly one week and has been available since November 9, 2026, aligned with the start of the Epic AI MegaJam (November 12–15). Epic stresses that this is an experiment to learn how to build the engine with multiple agents working in parallel; some agent-written code is still being cleaned up and parts of the web renderer remain prototypes.
Key new features
Experimental highlights include:
- Unreal Assistant: an in-editor panel for working with external coding agents such as Claude Code, Codex, Cursor or OpenCode, connected to Unreal MCP.
- Unreal MCP: now starts automatically and offers expanded toolsets (rendering, source control, profiling, debugging, level creation, Fab, and more).
- Unreal Canvas: a workspace to generate concept art, images, 3D meshes and video from prompts or scenes using your own API keys.
- Experimental Web (WebAssembly/WebGPU) support to run experiences in the browser.
- Significant expansion of Python APIs for automation and agent use.
Why it matters
Epic is accelerating AI integration into Unreal Engine development workflows and the engine itself. The preview arrives just in time for the MegaJam, where teams of up to five people can use as many agents as they want (AI use is optional) to create playable games in four days, with cash prizes and continuation grants of up to $50,000.
What changes in practice
Developers can already test agents inside the editor and generate content with Canvas. Epic notes the preview received a shorter QA pass than usual and encourages bug reports. The full 5.9 release remains planned for 2027, with refactoring of the prototyped parts.
Image credit: Epic Games | Source: Unreal Engine / official forums
By Grok
