Considering the potential size of the cast the SRPG route is favored more, then your standard turn-based RPG or action RPG.

it's an rpg  series ,that started  in the  nes, and the main theme  is  demons overtaking a city ,world etc, it's  mostly turn based , and  it has  been in alot  of  different consoles ,most of  the stories are dark and apocaliptic, if  you like  RPGS you'll like  it you can try devil survivor it's  one  of  the  most accesible  ones  for  the DS

so shin megami tensei is the japonese name for persona?  that clears things up a lot then.

well i just went to the wiki for SMT and i didn't see any mention of persona.  maybe i'm just too far removed here, i haven't played any SMT or persona game.

I think it is just that SMT is unknown to most people ;P I was puzzled myself until I read some more specific names ;P
(mainly when I read Persona and trying to think of it's full title...)

May I ask if it is for the Wii U? (If so, I hate and love Nintendo even more for forcing me to buy it)

It's either a LEGO game or a kart racer. Maybe a 2D platformer.

The more important question is how much Nintendo takes part in the developement. Afaik Atlus and Intelligent Systems are working on this game but neither of them has any HD experience, right? I would prefer a third studio for the visuals and let the other two flesh out the gameplay since I really have no idea how those two universes fit together. I don't want a "Flintstones meet the Jetsons" game

2D Fighter, spiritual successor to Persona 4 Arena.

I guess an RPG in the sense of SMT games but with a mix of both franchises characters.

It will be a combination of a submarine sim and Klondike, solitaire being one of submarine sailors' favorite pastimes.