We are creating a repository of resources so that people can build software or create videos or artwork using our material as their basis. We are making a virtual Moon colony and a website of related material, and inviting others to use that to make games or shows that take place in the colony, use our library to create objects or events that are placed within our hosted version of the colony as a 3d environment, write stories that draw on our material, et cetera. To facilitate that, all our libraries are open source and copy left. Currently they use GPL-3.
However, people who go to the effort to make things using our libraries are likely going to want to hold copyright on the derivative work, including making the source code closed. I would like to make it a license condition that they add models, textures, animations, and other similar component pieces they make to our libraries. But I am fine with it if they want to put a different license on their work as a whole so they can charge for it. I seriously doubt we will have many takers using our libraries otherwise.
It seems that if we change the license on the one folder in our GitHub repo that has 3d content, the one called 'blenderstuff', this might be achievable. I am the sole copyleft holder on all that material so I can make that change easily right now.
The project is at an early stage and I know very little about this realm. I just want to help people make cool stuff and educate the public about space. When it comes to legalities, I need a lot of help navigating it all.