this post could be seen as rude, it is just to help you not make very wrong decision.
(and keep yourself busy for 2/4 years without any decent result)

I don't expect people to tell me that i am the best by posting but more your kind of post.
sure you have this very great plan of the greatest game ever.
Well, it's not gonna happen anytime soon.
Kill your darling, scratch it, throw it away.
Start again, and now a much smaller game.
Don't dream about online madness, HD greatness and very cool fighting animation moves.
Because none of that will happen anytime soon.
Thrash that thought.
I don't remenber telling that i want to make the greatest game. I go step by step. I tried a mini-RPG, a shoot'em up, then a menu, than background, then animation, then an engine... and now i try to simply finish a game, not the greatest.
I think i can. I used 7 hour/day (4 years) for a PhD. 1 hour/day (2/4 years) is a joke. As for now, i just want to create, i'll see later for the best. I have realistic expectations depending on my previous results.
maybe you can use some of those backdrops and character sprites in an adventure game (
AGS) and experimet with storytelling.
maybe you could reuse some of thos backdrops and have something like breakout/asteroids/etc overlayed on top of it, in roughly the same theme.
So, the logic is to start from scratch although i have a program that allow me to copy/paste animations to make a new character.

maybe you could make a fighting game with colored rectangles as graphics, so you wouldn't need to worry about graphics AND animations AND programming (AND soundfx AND backgroundmusic AND etc.).
maybe you could use gamemaker or construct or some other gameeditor out there.
Programming: honestly, XNA is easy, even for beginners.
Graphics: SD is harder for me, my base materials are 3100 pixels Width.
Animations: 1) honestly not so good (look at the video) 2)Characters are DIGITALIZED!!!!!!!!!!! Nearly zero effort in animations!!! Good if this not obvious though.
Music: I know i can't do it, already found some musicians.
Conclusion: what you ask me is harder than what i did. Assesment of my skills was the first thing i have done, so i simplified my methodology to the extreme!!!!!
don't take this post as mean or anything, I just want you to succeed.
have fun.
I know you're not mean but sincere. Rendez-vous in two years and i'll prove you that i can finish my game, not the greatest game but at least a finished game.
