A moot point here would be the replayability of the game. I somehow feel that the old-school kill-fest games are much easier to just load up and sink into. Most of the story-based shooters are pretty linear (HL was one big tram-ride all the way). You played it once, poof, don't really feel like playing it again. But I still load it Duke and Quake2 (and UT of course) pretty often.