Why no Mario and Sonic non-sports crossover adventure game yet?

You're right we do need sonic boom but with Mario.
 
Sega, I believe, has reached out a couple times to Nintendo, but they rejected the idea as they didn't think it was necessary for them to meet in an action game. The Olympic Games series got the ok because they felt the crossover helped emphasize the Olympic spirit of different groups coming together, and that the friendly atmosphere was a perfect neutral ground for the two to meet.
 
Magikrazy said:
Sega, I believe, has reached out a couple times to Nintendo, but they rejected the idea as they didn't think it was necessary for them to meet in an action game. The Olympic Games series got the ok because they felt the crossover helped emphasize the Olympic spirit of different groups coming together, and that the friendly atmosphere was a perfect neutral ground for the two to meet.
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Also it made for a good April fools joke in 2007
 
Magikrazy said:
Sega, I believe, has reached out a couple times to Nintendo, but they rejected the idea as they didn't think it was necessary for them to meet in an action game. The Olympic Games series got the ok because they felt the crossover helped emphasize the Olympic spirit of different groups coming together, and that the friendly atmosphere was a perfect neutral ground for the two to meet.
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^ Basically this
 
They have.

It's called Star League.
 
The issue with having a crossover between the two without it being Olympic sport related is that then you have to find a balance between how Mario games play and how Sonic games play, which would be incredibly tricky.
 
Tsareena said:
The issue with having a crossover between the two without it being Olympic sport related is that then you have to find a balance between how Mario games play and how Sonic games play, which would be incredibly tricky.
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Or they could go the Sonic generations route.
 
That wouldn't have a very good flow. You might as well simultaneously be playing Super Mario Bros. and Sonic the Hedgehog, switching between the two each time you clear the level.
 
Honestly, I think a Sonic and Mario platforming crossover can work. It will just take some doing on what two mechanics of each of the game can work together. But I think Sonic Lost World would make a good basis. That is pretty much the most Mario-like Sonic game (Which was much of why it got some mixed response in the Sonic fanbase, but it really wasn't a terrible game. Though I'm not saying it's the greatest either.)

It would certainly take the best efforts of both Sega and Nintendo to make it work. Just Sega and Nintendo are more preoccupied with other things. And with things like the Olympics and Smash, it's not like we have a lack of Mario and Sonic being in the same game anymore.

I wouldn't mind however if they had crossovers between the two at least outside of Olympics even if it's not a platformer. What if Sega and Nintendo made their own separate mascot fighter outside of Smash Bros. that combines Sega characters (Like those you see in the Sega All-Stars Racing games) and Nintendo characters? The majority of the roster would still be Sonic and Mario characters. And it might at least partly put off the load off the fans who continue requesting more Sonic characters in Smash and Mario characters that aren't going to make into Smash anytime soon anyway. The game likely wouldn't be quite as good as Smash but could potentially make some people happy enough.
 
It has been a well known fact that Sega wanted to include Mario in Sonic and Sega All-Stars Racing on the Wii version or something but they dropped that idea or something along those lines.
 
They should have a Bowser and Eggman game instead where they are competing over who can take over the world first.