Okay, I know this topic ain't been used in a while, but I was having some fun on the weekend and ended up putting some serious effort into coming up with a RM set. I've never had anything I'd consider artistic talent (visual art, anyway), so be gentle, as I'm pretty happy they turned out even close to how I imagined them.
Almost called "Arctic Man", but for whatever reason I think Polar fits better. He's an ice/water type, with a stage that takes place around a set of icebergs. As you get deeper into the water, it gets darker and harder to see.
"Hover Man" because I thought "Blimp Man" was too silly and "Zeppelin Man" was too on-the-nose. I've actually got a full attack pattern set up for this guy, as well as some solid stage ideas.
Physical type, walks on his hands as his arms extend outward. The gears in his body allow the whole body to rotate, so as he walks across the room you have to time it correctly to slide underneath. Stage is a clock tower. I think I spent the most time just trying to figure out what color to make his eyes.
Out of curiosity, what direction would you point someone interested in making a MM fan game? Are there established engines or sprite design software that are common to use?