The League of Supernatural Gentlemen / Her Majesty's World of Darkness
While I enjoy roleplaying, I've never run a game, except for a single L5R adventure as part of a rotating GM system. Yet somehow I have found myself conscripted into running a game this weekend for the OURS Roleplaying Tournament. They were short one game and I made the mistake of mentioning that while I've never done it before I wouldn't mind giving it a go. The really bad part is that the idea I have is a crossover with all five of the new World of Darkness supernaturals (Vampire, Werewolf, Mage, Changeling and Promethean). So not only do I have to plot out an entire one-shot adventure and create characters, I have to make sure I have a firm grasp on the WoD rules AND on five different systems of mechanics for various supernatural powers, as well as balancing them all, in the space of a single week. Should be fun!
The worst one will be the Mage. Everyone else has "this power does this," but Mages insist on being complicated. Because it's magic.