I think 4 player DM sounds awsome. If you remeber the first DOOM, deathmatch was only for players, but it had the same "dark places" feature, so it was more of a man hunt. And a man hunt is what I want.
I can't wait for a simple CS type mod for this. 1 on 1 DM with real guns in dark corridors... with realistic windows and physics, it should be awsome.