Campaign theme could be "Lord of the Rings," in which hobbits don't use magic, wizards are demi-gods, and elves, apparently, do whatever they want. It seems, however, that the rules allow halflings to use wizards-staves. Do you go for it?
Or "supernatural World War Two" in which most characters are supposed to be firearm-wielding soldiers. You discover that you can unlock a psychic blast power (if you take the right perquisites), and use it more effectively than your machine gun, despite the game not being X-men themed.