My usual gaming group recently switched up DMs, and I decided to break away from our usual D&D paradigm and take up the mantle of Burning Wheel. So far, I love this system and can't say enough good things about it. I am currently using it to run a Westeros-based game. If you aren't familiar with the A Song of Ice and Fire series by GRRM, think low fantasy, human-only, high political intrigue, gritty medieval society. I suppose I would make one small addendum to this paragraph: Burning Wheel is an excellent system if you want a gritty game with infrequent and extremely deadly combat. Think of it as the anti-D&D.
Anyway, here's a basic rundown of the awesomeness:
* You don't get experience or levels. Your skills advance in a scaling fashion based on how often you use them in situations where failure is a risk.
* Beliefs and Instincts. The former is a small list of moral values or personal beliefs that say to the DM, "I want to encounter these things in game, or have these ideas challenged and tested for character development". Instincts are essentially If/Then, Always or Never statements that are immutable and unable to be affected by DM narrative. The DM can, however, tempt the player of the character to submit to their instincts in order to create an awkward situation, which the player is then rewarded for.
* Duel of Wits: Social combat, essentially. Two sides form an argument body and attack that body with a series of rhetorical jabs, parries, and sometimes even outright insults.
* Combat is very deadly, and is not entirely reliant on the dice pool available to each combatant. Even with wide gaps in skill, the underdog can outwit his or her opponent, get a strike or two in and end the fight.
* Artha: a point reward system that exists in 3 categories and can be used to alter dice tests, save oneself from the brink of death, and gain "epiphanies", which are like skill improvements but way more badass.
Just so I don't come off as a total fanboy (even if I sort of am right now): I will say that while Burning Wheel manages to use terminology that builds on itself and present concepts that are modeled in-game in an intuitive way, there is a bit of a learning curve not just for the DM, but also the players. It may require playtesting to get the hang of some of the more detailed parts of the game; Especially the detailed combat system.
I've only DMed 3 sessions of my game so far, and I can see things going much more smoothly as time goes on and my players and I learn more together. And really, considering the breadth of the system, the first session went surprisingly well.