Halo 1's co-op was fun as hell. I could play certain levels over and over again. Assault on the Control Room, The Silent Cartographer, The Maw. We used to have a hell of a time. For some reason I just can't bring myself to play Halo 2's co-op. I guess it's because the multiplayer. That and those jackal snipers, that just takes the fun factor to 0.