So it looks like the first developer to make a four-player platformer after almost twenty years was NinjaBee with Cloning Clyde. 
Kudos to them!
Rubang, have you actually played Cloning Clyde? Because I really like the art style, but I'm torn between thinking it looks like a ton of fun and thinking it looks like a serious headache. Apparently the co-op is always either online or splitscreen, so that makes it kind of different. I think I might have to download this one tonight :)
Anyway, now when someone says Nintendo is just ripping off Media Molecule, we can point out that Media Molecule just ripped off NinjaBee! (Though really, LBP looks a lot more like Nightmare on Elm Street to me than it does Cloning Clyde, so maybe Nightmare's developer should get the credit... And that developer is... hm... well what do you know? Rare.)
But really, this shouldn't be about who gets the credit for first cramming four players into a platformer. It should be about identifying possibly the most underrepresented genre of the past two decades. For those who haven't played LBP or Nightmare, believe me -- once you stick enough people into a platformer, it becomes a totally different genre.
They should be called platformer party games, or something like that. Two people together tend to cooperate. Go up to three or four, and the chaos goes up exponentially. All of the sudden instead of dying and starting over you're dying and waiting to come back to life while your friends continue onward (or stop to laugh at your crumpled remains). Like one of those levels in a classic platformer where you have to race the camera to keep from being pushed off the screen, suddenly you're racing every member of the group, trying to balance the risk of speed jumping over a bunch of spikes versus taking your time and falling behind. And if some frontrunner starts doing really well, and snagging all the coins -- that's when alliances start to form, death warrants start to get signed, and friendships get smacked aside into the nearest lava pit. Seriously, I can't describe how awesome these games can be.
NSMB could be the surprise game of the Wii, the beginning of a series tradition, like mario kart, that starts to get a new version every generation afterward. There are so many advantages to this type of game. It can be as deep as a 2d mario, but beginner players can also get into it without being in direct competition. If the levels are challenging and intricate enough it could double as a great single player game and a great party game.
