Captain of Industry

This game is not an Unreal Engine game (it uses Unity) but I still would like to point out a really interesting idea they had that is applicable to Unreal modding.

Captian of Industry decided to "DIY" all aspects of their mod support including mod hosting.

This gave them full control of the design of their mod licensing. Aside from allowing mods to select a license from the pool of typical licenses such as MIT, they also created two new licenses: COI-Open and COI-Keep (COI stands for Captain of Industry).

The most important part about these licenses is they both keep the work within the game's ecosystem. Even if a mod allow others to modify or build on it, these licenses do not allow the work to be taken and reused for unrelated projects outside the game. They allow mods to include code snippets from decompiled game code, as well as modified game assets, such as recolored textures or altered 3D models.

Without explicit permission that the other licences do not provide, mods using copies of game assets with or without modifications falls under the grey area of "reverse engineering" and may cause issues for you if a mod is using an asset that is not yours, but is owned by a third party such as a marketplace plugin author that you got the asset from.

COI-Open

COI-Open lets other mod creators freely use, modify, and share the mod within the Captain of Industry ecosystem, as long as credit is given, derivative works remain under the same license, and the work is not used outside the Captain of Industry ecosystem. The license does not require authors to publish their source files, project files, or any internal development files unless they want to. The license only defines what others are allowed to do with the mod files they publish.

COI-Keep

COI-Keep allows players to use the mod normally, but preserves more control for the original author. Derivative works are not allowed without permission, with one important exception: limited community maintenance.

Limited community maintenance means that if a mod becomes incompatible with the game and the original author is no longer active or does not address the issue within a reasonable time, the community may publish fixes to keep the mod working. This exception is only for compatibility and maintenance fixes, not for adding new features or taking over the mod. The work still belongs to the original author.

If the original author returns and updates the mod, the community maintenance exception ends, and the author resumes control over publishing updates, unless the mod becomes broken again in the future.

COI-Keep is meant for authors who want to keep control over their work and do not necessarily want to make their mods fully open, while still allowing the community to keep the mod alive if the author moves on from the game or becomes unavailable.

Extracts of text taken from https://www.captain-of-industry.com/post/cd-55