I just picked this game up from Steam this weekend. It only cost $15! It is very fun, and very high quality for the cheap price. The only problem is there are not enough people playing it, so you have to wait in the lobby forever at times to get in a game. They have several game types including DM, TDM, CTF(retrieval), Domination, and a game like Sabotage (I forget what they call it). There are also 4 coop missions that you can play with friends or alone. Check it out:
http://store.steampowered.com/app/27330/
http://xboxlive.ign.com/articles/110/1104787p1.html
http://store.steampowered.com/app/27330/
http://xboxlive.ign.com/articles/110/1104787p1.html