The VGChartz list of the best co-op games for every system ever.

[elgefe02]

Johnny B said:

Goldeneye is great, but I don't remember a coop mode in it. Unless you use one of the controller schemes where you use two controllers, and have one person use either controller, but that would be... difficult.

Anyway,

SNES: Lost Vikings and Lost Vikings 2. I played Lost Vikings 2 in a hotel (pay per hour using... Lodgenet?) for an hour or so with my brother. We were hooked, so we rented Lost Vikings once we got home. Finally, after ten years, I finally found Lost Vikings 2 in a used game store. My bro and I beat it this summer. Great puzzle games by Blizzard.

Also SNES: My friend and I have had some fun with Darius Twin, an airplane side-scroller like Gradius.

NES: Gradius (never played it, but I think it's two player) and Lifeforce. Both are airplane side-scrollers, I believe. 8 Eyes has a really cool concept--player one is a man Orin, and player two is his bird Cutrus. The game is like Mega Man in that you can go to stages in any order. The downside to the game is that once you beat it, it starts you over for a second quest. Not so bad. Then you beat it again and it starts you on a third quest. That's when my brother and I quit playing--we didn't think it would ever end (I think it does after three, though).

Also NES: Mega Man 3 has some cool cheats where you hold up or A on controller 2 and your dude can jump really high or live forever or something, but they only work on the NES version.

Gradius is not a cooperative game