(Note, this is assuming that you want to have some sort of story to your game. :])
Now we're talking about some very fun aspects of creating a character, and at the same time, the world where this game takes place.
A mega-man styled game doesn't necessarily need to be robots and energy shots and the like. It could go into a fantasy-like setting too. (Take note that keeping character in context to their world helps maintain a more realistic nature instead of, say, lightsabers from Star Wars in an ancient world of magic swords and whatnot.)
I think you need to sit down and think of concrete, principle ideas of your game first (like the main character and his powers, the setting of your game, the bad guy, power-ups, enemies, etc.) and then hop into creating it so that your vision remains uncompromised. Not to say that getting ideas from Blob's edit is bad, in fact, it's great to get inspiration from others ideas. You just need to know how much you're willing to change, and how much you want to stay close to your original idea.