And this is the world of Mages.

 In Mage: The Ascension, you play, of all things, a mage! But that's not the end of the fun, of course not. Your magic is limited by the energy known as 'Quintessence', the energy of magic and the universe, and by 'Paradox', the warping of reality by the casting of magic. The more you cast, the more you accumulate Paradox and the less Quintessence you can channel. The more Paradox you accumulate, the more reality is ready to have a seizure in your immediete vicinity from the seizures you've already thrown around with your magic.

 All in all, an interesting diversion when you have nothing better to do, and in all ways much superior to Vampire, another game by White Wolf.