I think the target audience is adults who remember the old NES/N64/Sega games, but still fun for newer generations of kids between 12+. So, we have to keep it clean fun

For graphics, I think we can support modern cards within the last year for some sweet eye candy.. However, it should be possible to also support older cards as Ogre supports material fallbacks.
PC Target platform -
CPU ~1.8-2GHz
Video - GF 4
Memory - ??
Harddrive - ~100MBs
Network Speed - ??
Now, that is just the bare minimum computer that it should run on.. Of course, we can provide more shaders for more advanced systems. No plans for Xbox live at this point, however, if the game ever got sponsered from a console maker (unlikely, but I'm also optimistic), I would want a complete port, not just Xbox-live. Plus, I think the game would be more suited, stylistically, for the Nintendo Wii then anything else.