I said Vietcong; only because it's online gaming community is dead. Urban Terror still has a massive amount of players, and SoF2 has some very old clans that still play alot, even comps.
I would hate to see Urban Terror disappear, it's 100% free, forever, no strings attached. It doesn't make profit at all and is run on donations (And site ads, probably rents servers too I presume, but still; doesn't charge the average player), and has been running for 9 years. I think this is just awesome, the creators must have put so much effort into this and the community is now very large. The game itself is not my favorite cup of tea; but clearly would appeal to the Quake player or the TF2 classic or CS Classic player.