I'm probably going to have to say Halo 3 was my favorite game of all time. Like @orc said staying up playing custom games with my buds all night, that was my shit man. It was really cool cause that game was one where you could do that type of shit and mess around, but at the same time turn around and go murder kids in team slayer if you had a group of friends. It also got really cool in MLG and watching all the teams play and even getting paired up with some of the MLG teams. It was honestly one of the best experiences of my life and I made so many friends through that game. Seriously is the saddest thing ever that you can't even play some playlists because the lack of people playing it.