well yes mostly gaming. Then depending on how long they last there could be some other stuff too. Like once we had a lan party for like, umm, about 40h. So u need to be just crazy if u can spend all that time playing with computers. So we did other stuff too, like playing pool and table tennis. But ofcourse no sleeping! (well actually there were only 3 of us who didn't sleep at all, and I'm proud to be 1 of them)
And yes mostly FPS. But we also play some strategy games, not too much though. And ofcourse u need different kinds of FPS games, like some which are like few shots = kill and then some stuff like UT. And then lot's of game modes. For example in UT there is a few good game modes, assault being my fav.