Colonial Marines Universe (CMU) is a multiplayer sandbox game set in the Alien universe. It is a fork of RMC14, which is based on Colonial Marines 13 (CM13), and is built in C# on the RobustToolbox engine.
This repository contains the game's code, maps, and resources. CMU builds on the work of its upstream projects and contributors, with asset credits and licensing recorded in the corresponding metadata files.
Join the CMU Discord to get involved, discuss the game, and coordinate contributions. For bugs, feature requests, and tasks needing help, visit this repository's Issues tab.
Contributions are welcome across code, maps, art, sound, documentation, and testing.
- Check existing issues before reporting a bug or starting work. Discuss larger changes in an issue or on Discord.
- Read the contribution guidelines for code conventions and pull request guidance.
- Keep your changes focused and test the behavior they affect.
- Open a pull request using the pull request template. Explain what changed, why, and how you tested it. Include screenshots or video for visible changes where useful.
When adding or modifying assets, preserve their attribution and license metadata. See License below.
- Git, including submodule support.
- The .NET SDK selected by global.json.
- Python 3 for the repository's build setup scripts.
CMU builds on RMC14, CM13, Space Station 14, and RobustToolbox. Thanks to the developers, artists, mappers, and other contributors whose work makes these projects possible. Individual asset credits are recorded in metadata.
The May 1, 2026 licensing cutoff was introduced in commit 08ae7902c0c4 ("Revise license information"):
- The vast majority of code implemented before May 1, 2026 is licensed under the MIT License.
- All code implemented on or after May 1, 2026 is licensed under the GNU Affero General Public License v3.0 (AGPL-3.0), unless noted otherwise.
The repository's LICENSE.TXT was subsequently changed from MIT to AGPL-3.0 on May 13, 2026, in
commit f41c414ca0ec. The cutoff above comes from the earlier README change.
Most art assets are licensed under CC BY-SA 3.0, unless stated otherwise. Each asset's metadata records its license and copyright information; consult that metadata for the terms that apply. See this example asset metadata.