Sounds like a good idea, I would love to see this finished, I have always thought that someone should make one thats online for real, but its always been.... difficult, and legally questionable. A fan game would be great though, anyway, hope you can get some awesome sprites and stuff for it. In about a week or so I should have my brand new comp, so if you need a mapper I may be able to help a bit, but no guarenties. Im also good with photoshop (cant sprite though, and im really bad at pallets).
Anyway, i wont devote myself to this project, but if you need something here or there, i wanna see this project actually completed.