Everyone should read One Punch Man.

What do you mean by a roleplay based on it though? I mean, it's not like most super settings where the question is how one overcomes the challenge - we know what's going to happen, it's right there in the title. And characters aren't really defined by their powers, but by their attitudes goals and outlooks. The underlying theme is that power doesn't matter.

I guess what I'm saying is, an OPM RPG should be about a superhero doing their weekly shop.