Good Co-op games?

[wariofan1]

If you're into platformers and don't care about a game being childish; Kirby: Return to Dreamland (known as Kirby's Adventure Wii in Europe). Just finished it 100% on both modes, and I have to say, it's simply the best Kirby game ever made, the best platformer on the Wii, and the best game of 2011. That is if you're into platformers, especially Kirby. The fact that co-op makes you able to play as recognized bosses like Meta Knight and King Dedede makes it 20% cooler.

[Deleted]

I play quite a lot of co-op with a buddy of mine (we look specifically for co-op games with solid campaigns every now and then). I'll list a few PC titles;

Gears of War 1
Resident Evil 4
Fear 3 (no person in their right mind spells it F3AR)
Left 4 Dead 1 and 2
Portal 2 (PLAY THIS)
Rainbow Six Vegas 2 (this one is really solid)
Splinter Cell Conviction
Call of Duty World at War has a surprisingly solid co-op campaign

I know that there are plenty of other quality games, like Diablo for instance, but we haven't played everything yet ^^

[Arrowstormen]

Is Left 4 Dead (2) scary for real, or?

[Mechazod]

The Adventures of Cookie & Cream (PS2)
Fatal Fury (was re released in SNK Arcade Collection and Fatal Fury Battle Archives Volume 1 if you need a modern port of it)
Capcoms Disney Magical Quest series (SNES and Genesis)
LittleBig Planet 1&2
Katamari Damacy and We Love Katamari (PS2)
the Army of Two series had really fun co-op, almost reminded me of a 3D Contra (PS3/360)
Ratchet: Deadlocked (PS2)
Jet Force Gemini (N64)
Capcom Classics Collection 1&2 (plenty of co-op arcade games such as Final Fight and Eco Fighters)
Super Smash Bros Brawl (the adventure mode has co-op)
Secret of Mana (SNES)
the Lego Starwars series of any of the Lego games really
I never tried it yet bit I think Titan's Quest had some sort of LAN mode to it (PC)
Teenage Mutant Ninja Turtles 2 and 3 (NES)
Duke Nukem 3D (PC)
Donkey Kong Country series (SNES)
Freedom Force (PC)
the Streets of Rage series (all three re released in Sonic's Ultimate Genesis Collection)
Valkyrie Profile 2 from what I remember had a co-op mode (PS2)

[Jon]

Trine 2 is awesome.

For more ideas:
http://www.co-optimus.com/

[hordak]

Magicka was quite fun in co op for me. It's a bit short though.

[Hiricine]

Dead rising 2, especially off the record.