Mario has jumps, double jumps, triple jumps, backflips, and long jumps. He's a jumping machine. So what if he has one punch and one spin move?

I dont think so, but side 2d side scroller is(SUper Mario World). I consider Galaxy and Ratchet "adventure".

All I'm getting from everyone is that Mario games are platformers and Donkey Kong games used to be? That's it? Does anyone here consider ICO to be a platformer? It had more jumping and less fighting than most Mario games. My point was to see how in a 3D gaming world can a platformer still be a real genre. Back in the days, everything was a platformer, whether there was tons of shooting, sword fighting or whatever. Ninja Gaiden, Contra, Castlevania all platformers. Nowadays, you need to concentrate almost solely on the jumping aspect for there to be any consideration of a platformer or at least put a cute mascot in the role.

^ Galaxy and Ratchet are nothing alike CDiablo. Galaxy is a Platformer, R&C is a Shooter/Platformer or Action/Platformer.

Someone please explain to me how they think SMG isn't a platformer, because honestly the mind boggles.

The real definition of a platformer in my mind is a game where the most important aspect of the play is the movement of the character rather than the actions performed by the character.

In Mario for example, jumping, flying through space and all the rest of it is based on puzzles of the characters movement. Sonic is all about running and jumping as well.

Games like Contra and Castlevania are more 2D action games than platformers by my definition.

Contra, Castlevania and Ninja Gaiden were NEVER classified as platformers, even when they were new

Contra was a shmup, specifically a run-n-gun type shmup
Ninja Gaiden and Castlevania were both classified as action-adventure games at the time of their launches

Oh, and how can you really say that ICO has more jumping than a mainline MARIO game?  Even Sunshine was more jump-centric than ICO was. 

Well 3-D platformers are very rare due to the 3-D control scheme. With the addition of the third dimension, platforming's become way easier, so they usually throw in some more weapons and gameplay elements to make up for that. 3-D platformers have never had some of the ridiculous jumps that even SMB1 or hell, the Lost Levels, had.

Ok I'm sorry, ICO has slightly less jumping than a Mario game but has more focus on platforming aspects since combat is kept to a bare minimum. Is ICO a platformer? Is Tomb Raider a platformer? I remember an awfully lot of platform jumping and not too much combat in Tomb Raider. Seems to me in both of these games, climbing and jumping were kept as a primary focus the entire game with combat entirely second. In fact in ICO, the only way to actually kill your character is to miss a jump and fall to your doom.

There's a new game by EA called Mirror's Edge which is going to have you attempting large platforming jumps in first person view the entire time. Is it a platformer? 

What do you guys consider the classic megaman?

^Classic Mega Man=Action Jump N Run Super Mario Galaxy=Jump N Run Assassins Creed=Action Adventure with Jump N Run elements ICO=Jump N Run with Action Adventure elements everything above only imo :)