The C# framework behind RimWorld's move off Unity is now free on GitHub

BRUTAL, the C# framework Ludeon thanks for helping make its Waylith engine possible, is now public on GitHub. It is MIT-based and royalty-free, and asks for a logo and credit in return.

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The C# framework that Ludeon Studios credits with helping RimWorld leave Unity is now public. BRUTAL went up on GitHub on 14 October, two days after Ludeon announced update 1.7 and its own Waylith engine, and was introduced on r/gamedev on 15 October. It is free to use in commercial games, with no royalties, and asks for credit in return.

The README calls it "a free, open source C# framework for making games, or your own game engine." RocketWerkz built Kitten Space Agency, its free pre-alpha spaceflight sim, directly on it. The same README says "Ludeon built their Waylith engine on it to move RimWorld off Unity." Ludeon's own announcement is a little more modest: it describes Waylith as "our own in-house engine built by Ludeon Studios" and closes with thanks to RocketWerkz, "whose Brutal framework helped make Waylith possible."

What is in it

At the bottom sits a custom interop layer that gives C# direct access to native libraries. Around it are allocation-free collections and strings, unmanaged memory, maths types, a job system, logging and localisation, plus bindings for Vulkan, OpenGL, GLFW, SDL, Dear ImGui, FMOD, OpenAL, RakNet, Jolt and Box2D. Each folder ships as its own NuGet package under the Ahwoo.Brutal name, so a project pulls in only what it uses. What it leaves out is as deliberate: "There is no editor, no scene graph and no renderer, and we're not adding them," the README says, and pull requests that drift from that will be rejected.

The getting-started notes ask for the .NET 10 SDK, a Vulkan 1.3 capable GPU if you render, and Windows or Linux. Asked about platforms in the Reddit thread, the account thedeanhall (Dean Hall is on the founding contributors list) replied that the team develops on PC, Mac and Linux and has had game builds running on Xbox, Steam Deck and Android. Project files and build scripts for compiling the repository yourself are listed as coming; for now the code is there to read and fork, and the packages are the way in.

The licence

The BRUTAL License v1.0 is MIT with an attribution clause, and the copyright belongs to Ahwoo Limited. A shipped game has to put the copyright notice in its credits, show the BRUTAL logo before gameplay starts and ship a NOTICE.txt file. Studios that do not want the logo can arrange a separate commercial licence, and the requirement is waived for non-profit projects. The README says the licence is not OSI approved because it has not been submitted yet, and that the team intends to do so. One Reddit commenter compared the splash screen to Unity's; the thedeanhall account answered that waivers are available and that the point is crediting the people who made it.

Besides RimWorld and Kitten Space Agency, the README lists Torpedia and Art of the Rail from RocketWerkz and Afterskies from Floating Origin Interactive as built on BRUTAL. On the RimWorld side, Ludeon says 1.7 runs 2 to 4 times faster in its tests, loads 1.6 saves, and keeps the vast majority of mods working unchanged. It is on the unstable beta branch for now, while the main branch stays on 1.6.

Sources

Image: Ludeon Studios