1. Both L4Ds
2. Both Army of Twos
Besides those I can't think of any co-op shooters for the 360 for them. I've already tried to convince them of Borderlands, Gears of War 1&2, all Halos, and Dead Rising 2, but because of my dad they won't play them.
So can anyone recommend me some more co-op/shooter/360 games?
Thanks for all replies.