Yeah, there's lots of active servers - but it's dying. I think many servers are filled more by bots than people. That said, it's great fun if you know where to play.
RTCW is also fun on singleplayer mode.. and it runs natively on GNU/Linux.
It's been dying for the past decade. People still play it.
That got my attention as well. There was another person with the game in their dock, which I noticed first. I may have to install it from Steam and play it again sometime..
I had the same exact response. "RtCW is 13+ years old!?" I spent so much time with that game.