Even if Portal 2 was published by EA you should let it slide. Without a doubt. |
Other than that most have been mentioned in this thread already.
Little Big Planet 1&2 är loads of fun for a long time. Although I've had the most fun with it when I've been playing with my gf. Not that much experience with online co-op. So I guess it's down to who's your companion.
Dead Nation is also great. Get the DLC at the same time because you'll want more. It's better than Lara Croft and the Guardian of light which imho is better as a single player game.
Trine didn't work for me on console. Try the demo and if it fits go for it because it's a good game. Never tried it on co-op though.
Red Dead Redemption offers great multi and co-op.
Spent a lot of time with Uncarted 2 when it was released. Then something happened with the servers, everything froze and my all weekend, all nighters grinding was lost and I was reset to zero. I got devostaded. But uptil then it was great but could've done with more co-op maps. Maybe it's been fixed for UC3.
And don't dismiss MW2 and MW3. The Special Ops are quite underrated and forgotten co-op.
Next up for me is probably Castle Defenders.
I sleep on my back because it's good for my spine and coffin rehearsal.