Best CO-OP Games?

Saints Row The Third.

Saints Row: The Third

Borderlands 1,2

Portal 2

Diablo 3

If you enjoy puzzles. Portal 2.

dungeon defenders

FEAR 3

Portal 2

Sven Co-op (HL1 mod)
Torchlight 2
Magicka

Realm of the mad god

i wanna say borderlands 2 is the best i've ever played

Lord of the Rings: War in the North
Terraria

Most of the ones that I would say are already written ^^

Borderlands 1 + 2,
Dead Island,
Dark Souls,
Transformers (the first one) the campaign is CO-OP

boderlands 2

World of Warcraft if you have 4 good friends to play with. Seriously.

Serious Sam

System Shock 2

red alert 3
shogun 2
supreme commander forged alliance

best coop experience I ever had was in splinter cell conviction

I see you like FPS games, so I suggest old Wolfenstein: Enemy Territory and quite new Arma 2 CO.

Orcs Must Die 2
Trine & Trine 2
Nation Red
Torchlight II

already said my favorites(killing floor,dung defenders and left 4 dead 2). I can say magicka for something different. Is a lot of fun coop and a lot of hours of gameplay. If you want a fps dead island. Haunted hell's reach is third person shooter cheap and similiar to killing floor.

Rainbow Six Vegas and Ghost Recon Advanced Warfighter, Dawn of War II

SERIOUS SAM! =)

Dead island and Torchlight 2

Dead Island, Europa Universalis series, LEGO series.

Torchlight 2 =]