Epic ships Unreal Engine 5.9 preview built by AI agents

Epic Games released the Unreal Engine 5.9 MegaJam Preview on November 9, a build the company calls "the first Unreal Engine release built primarily with agentic workflows." Epic announced it on its developer forums.

Epic said the build 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," the company wrote. Agents wrote the web platform code starting from the HTML5 platform Epic retired with Unreal Engine 4, while engineers directed, reviewed and tested the work.

For creators the feature that matters is Unreal Canvas, an experimental tool available in Unreal Editor and as a web app. Epic says Canvas generates concept art, images, 3D meshes and video from prompts, reference images or a developer's own scenes while preserving composition and camera perspectives, and tracks the work through connected prompts and generation graphs. Developers connect the AI models themselves with their own API keys.

Three more experimental features ship alongside it. Unreal Assistant puts coding agents such as Claude Code, Codex, Cursor and OpenCode in an in-editor assistant panel. An expanded Unreal MCP now launches with the editor and adds toolsets for rendering, source control, profiling, debugging, gameplay testing, geometry, audio, UI and level creation, plus a Fab toolset that lets agents install free or purchased assets. Projects can also run in a browser through WebAssembly and WebGPU, though that needs a source build and a C++ project, and Epic says Chrome gives the best experience.

Epic was open about the trade-offs. The preview had a shorter QA pass than usual, some agent-written code is still being cleaned up, and parts of the web renderer are prototypes Epic plans to refactor before the full 5.9 release, which it says is due next year. Epic has also confirmed that Unreal Engine 6 will drop Blueprints and Actors.

The preview is timed to the 2026 Epic AI MegaJam, which runs November 12 to 15 with a theme-reveal livestream on November 11. Teams of up to five people, plus unlimited AI agents, build a game in Unreal Engine or Unreal Editor for Fortnite, and standout entries can earn development continuation grants of up to $50,000, according to Epic's MegaJam page.

Canvas runs on a developer's own API keys, so Epic is not selling the AI models. The bet is narrower: if directing fleets of agents can hold up on a full release, Epic ships more UE5 fixes without slowing Unreal Engine 6.

The Unreal Engine 5.9 MegaJam Preview is available now from the Epic Games Launcher, GitHub and Epic's Linux download page, and the MegaJam's theme-reveal livestream airs November 11 at 2 PM EST.