That's a tough question, really. In actuality, we can make our own type, nonfiction music if you will, because of the nonfiction setting. However, I imagine it to be a sci-fi type of music.
Am I the only one wondering what exactly "nonfiction music" is supposed to be?
Also: If you need to solicit people to program and create the visual and musical content for your game... what exactly are
you contributing to the project? It sounds like you're not really bringing much to the table except "design" and trying to see who on the Internet will do the rest of the work for you. At the very least, you will need extensive design documents and plans to present to people, especially if design is all you're doing. Do not ask people to start programming, drawing, or composing for your game until you can tell them precisely what it is they're supposed to be programming, drawing, or composing. You do not seem to know any of this yet. My advice? Go back to the drawing board, write up some
extensive design documents (plot, setting, game mechanics, aesthetic sense, anything that you need),
then start asking around for help, because right now, you have nothing to show.
In my very honest opinion, coming to a message board with a vague idea about a game, and assuming the game is going to somehow turn out "very profitable" despite little description, presumably little experience, no team, no visible portfolio, nothing to vouch for you, and few relevant skills to bring to the table yourself... that really is the height of arrogance. You don't even seem very clear on what you want your own game to be, and don't have a handle on any of the technical aspects (why do you assume it should be C++ even though you aren't a programmer, or MIDI even though you clearly know little about audio?), so why are you assuming your own nebulous, wispy design ideas are so lucrative?
By the way: Why in God's name would you be considering MIDI in 2011? Speaking as a person who knows at least a
little bit about digital audio, this is
the worst possible option you could have thought of. The only reason to distribute music on MIDI is if you literally are putting it out via floppy disk or 56k modem or something. It's not 1994, and we're not running DOS. You can't even guarantee a MIDI will
sound similar across different systems (unless you put a lot of work into that, of course). There is virtually no reason to even consider it, trust me.