The Quake3 mod: Urban Terror discord server.
"Where Quake Meets Reality"
Urban Terror is a free multiplayer first person shooter, that will run on any idtech3 compatible engine. It is available for Windows, Linux and Mac OS.
Read more about the game on its wiki page: https://wikipedia.org/wiki/Urban_Terror
Join its awesome community, developers and players in regular events, daily pickup games and chats.