Ahwoo and RocketWerkz, companies of DayZ creator Dean Hall, have published BRUTAL, the C# framework under RimWorld’s new Waylith engine, on GitHub. The repository appeared on 15 October 2026, and its README lists Waylith among the projects built on it. Earlier this week we reported that RimWorld is moving from Unity to Ludeon Studios’ own Waylith engine; Ludeon’s announcement did not say what Waylith was built on.
Ahwoo Limited holds the copyright, and the README credits the RocketWerkz Enterprise team as BRUTAL’s makers. The repository describes the project as “a free, open source C# framework for making games, or your own game engine”. Every commit in its public history is dated 15 October 2026.
No editor, no renderer, by design
The README says BRUTAL has no editor, no scene graph and no renderer, and that the team will not add them: “BRUTAL is not trying to be a general-purpose engine.” It compares itself to a kernel instead. Its core handles interop with native code, memory, collections, strings, maths and concurrency, with an emphasis on avoiding allocations and overhead. Around that core it wraps native libraries that developers can call from C#:
- graphics through Vulkan and OpenGL, with ShaderC/Slang, ImGui and glTF support;
- windowing and input through GLFW and SDL;
- audio through FMOD and OpenAL, networking through RakNet, and physics through Jolt and Box2D.
It currently targets Windows and Linux, and needs the .NET 10 SDK and, for rendering, a GPU that supports Vulkan 1.3.
The README frames the project as a question of control, arguing that developers have handed a great deal of it to companies whose interests may not match theirs. BRUTAL is meant to let a studio build its own engine “without having to spend four years building the foundations first”. It also warns that this is not the easy route: the framework makes no architectural decisions for you, and “It’s called BRUTAL for a reason.”
RimWorld and five other games built on it
The README lists six products that use BRUTAL:
- RimWorld (Ludeon Studios), through its Waylith engine;
- Kitten Space Agency, Torpedia, Art of the Rail and Gruntz (RocketWerkz), built directly on BRUTAL;
- Afterskies (Floating Origin Interactive), also built directly on it.
It repeats Ludeon’s figure of two to four times the performance of the Unity build of RimWorld. That is Ludeon’s own measurement, published with the 1.7 test build, and has not been independently verified.
Royalty-free, but the logo must show
BRUTAL can be used, modified and distributed free of charge, including in commercial games, with no royalties. The licence is described as MIT-based, with an extra attribution requirement. A game built with BRUTAL must:
- include the BRUTAL copyright notice in its credits or equivalent;
- show the BRUTAL logo before gameplay starts;
- ship the project’s NOTICE.txt file.
The logo requirement does not apply to non-profit projects or where showing it would harm the application’s purpose, and a separate commercial licence is available on request. The README also says the licence is not yet approved by the Open Source Initiative because it has not been submitted; the team says it intends to submit it. Until then, the “open source” label is the developers’ own description, and studios that need a formally approved open-source licence should check the terms themselves.
Hall’s case for frameworks over engines
The release follows a plan Hall described almost a year ago. In a Game Developer interview published on 20 November 2025, he predicted that frameworks rather than big engines would shape game development, and said Brutal would be made open source through a company called Ahwoo. He also argued that large language models make text-based programming in structured languages such as C# more practical, mainly as a way to look things up quickly. He and Kerbal Space Program creator Felipe Falanghe said they rarely copy code generated by these tools.
BRUTAL is not a replacement for Unity, Unreal or Godot for a team that wants an editor and a renderer out of the box. Its audience is studios that want to own their technology, as Ludeon now does with Waylith, without writing native bindings and memory handling from scratch. Its contribution guide asks for small, tested changes and says the project’s scope will not change. The repository had no tagged releases when we checked, and how many outside studios adopt it, beyond the three named in the README, is still an open question.