Burning Wheel

From The Burning Wheel Wiki:

The Burning Wheel is an award winning fantasy roleplaying game written by Luke Crane, in which players take on the roles of vibrant, dynamic characters whose very beliefs drive the story forward.

Starting with a simple d6 die pool mechanic, this game intuitively builds on its core concepts, evoking a pitch and tenor in play uncommon in roleplaying games. It details solid, dramatic systems for task resolution, advancement, trials of belief, tests of nerve, searing social conflict, dangerous sorcery, miraculous faith, and brutal, gut-wrenching martial combat. Behind the dice, player decisions drive the game's systems. The choices tangibly affect every outcome, from glorious victory to ignominious defeat.

The mechanics are presented in an easy-to-read writing style, with plenty of insight and advice from the designer. If you're not careful, Burning Wheel will change the way you play roleplaying games.