I’ve been playing all of those in multiplayer mode too. Gears of War in particular, has three different multiplayer modes, one of which is novel (to me at least, as a long time PC gamer); the ability to play the single player campaign cooperatively with another human. I used this a couple of times on boss levels that were too difficult for me to manage with only the help of a computer partner. Nicely done, Epic.
If you’re on XBox Live, send me a message or a friend request; I’m “GongaThrash” (my old D&D handle from high school).