After reading through a couple of posts, I must admit that I'm a little disappointed that no one brought up any original storyline let alone stating genres, words, actions as such as werewolves, pimps, etc. What would be the storyline in that? What would these fight for? What caused World War III?
I'd like to offer my two cents and hope it'll help anyone else. Roleplaying isn't about genres, it's about the storyline. What happens in a story that caused it to start, and why did it start revolves around ideas and imagination that will expand our thoughts over the horizon. Let's take an example of pimps and werewolves, they don't start the story by themselves, they actually have had to commit the action like a war over some moral values or whatever, in order to start the storyline.
Before you think of these things, think of the storyline and how would it start, why would it interest people into roleplaying their characters in this storyline. The main factor of the roleplaying is usually the storyline. If anyone wants to know an example of it, please feel free to let me know and I'll provide you an example of the storyline.
-- Grey