After a long period of silence, it seems a lot was going on behind the scenes for Unvanquished and it's now properly open source all the way through.
Originally forked off from another game, Tremulous, which has a lot in common with the Natural Selection game. Two opposing sides of Aliens vs Humans that mixes first-person action with a little strategy with some building. Unvanquished was an effort to continue Tremulous with more modern features and it appears to be close to a new release.
In a long round-up blog post, a lot of effort has been put into splitting up assets and tools needed for Unvanquished into their own respositories, making it easier to track down and properly sort out licensing. Lots didn't have a license, or one that was problematic for the project. Now though? They're announcing that Unvanquished is now "fully open source again, from engine to game code, from models to textures".
Part of their move to ensure it's open source comes from how many games are now on Linux or can be run unofficially, so they want to continue to show off free and open source gaming. So it's a cross-platform game across Linux, macOS and Windows that's also fully free and open source. It took a few years and lots of effort to do but I for one appreciate how far they went to ensure it.
The best news is that a new release, Unvanquished 0.52, is almost here. Sounds like it's going to be a big one too, as they mentioned it's going to need multiple blog posts to cover. Exciting times.
See more on the Unvanquished website.