While there's no real need to play Super Mario 64 in co-op, there's nothing wrong with wanting to have a friend along for the ride. Now, thanks to a hack by YouTube user Skelux, you can play with a friend.
Skelux's hack (or 'patch') of the Nintendo 64 classic adds a second player, 'Blario', to the game. Yep: Luigi has been left out again, but as the YouTube video politely points out, Blario isn't such a bad guy.
Watch the video below. There are a couple of neat tricks you can pull off with two players, but they're hardly gamebreaking. The video also claims you can control both characters alone for an "extra challenge".