Quintessence

Quintessence is a simple gaming system. It focuses on flexibility, strong role-playing, and a totally manic resolution mechanic. It is designed for settings and games where all the players are of comparable power. They may certainly be a great deal more powerful than the rest of the cast, however!

The game is designed for people who have played a pen-and-paper game before, and it assumes you know what dice are, and the difference between players and characters, and what GM stands for and such.