Free and Open Source Software

So i was looking around some stuff and discovered AssaultCube, i do remember hearing it's open source so i thought that topic might fit here (feel free to correct me if i am wrong)

I have been wanting to try that for sometime now but was worried if the game was dead or not (i won't mind if the playerbase is small or big, all i care about is if there's servers still running and if there's still people in it) and this might be a dumb question to ask since idk if there's any AssaultCube players or if there is even anyone here that knows it's existence but is the game alive at all? if not, are there alternatives that are more active? (AssaultCube-like or not, just any open source shooter game will do fine and i've already tried xonotic, good game and will play that again sometime lol)