This last weekend I played session of Mouse Guard with my Saturday group. Mouse Guard is based on the comic by the same name, and it's about mice with medieval-level technology struggling to survive the seasons, the weather, the wilderness, wild animals and each other. I feared the game wouldn't go very well, as our group has varied tastes regarding subject matter, playstyle and just plain quirky preferences. But I ran it... fumbled through it really, and yet it was well recieved. The reasons varied, from enjoying the background to a strange fascination with the rules system and probably other reasons as well.
I doubt that the game would hold up for the long haul (for this group), but the session we had was fun. Things seemed focused and energetic. Things kept happening and dice kept rolling and people seemed to enjoy their characters, pregens though they were. Because of the structure and because we were unfamiliar with the system, the first session went pretty quickly, and so we followed it that same night with a second "session", and my group seems eager to give it another go next week and see how things turn out. The overall system is pretty simple and people mostly liked it, though the "conflict" system, which in this case was used in a combat, was cited as being "too abstract". I think this was probably specific to combat. If it had been an argument or a chase or something (which all use basically the same rules) it might not have been perceived as a problem.
People did seem to like the advancement rules, though, which basically require X successful uses of the skill and X-1 failed uses of the skill, where X is the current skill level, to advance a skill. It allows for an "organic" growth of character skill, such that skills only advance if you use them, but also encourages players to try difficult (ie, "dramatic") things in the story in order to earn those "failed" checks. (For those unfamiliar with this sort of system, I should point out that there are no meaningless, "fail-to-pick-the-lock-try-again" failures which means that failure always has significant and hopefully interesting consequences.)
Now, as the GM, I didn't give the challenges the thematic depth that they could have. I didn't focus on the characters' beliefs, instincts, goals and traits as much as I could have, though nobody seemed to notice. The players also didn't earn "checks" against their traits during the sessions, either. Part of this is my fault for making the "GM Turn" so short. There really wasn't much room to hit those traits, but partly I think the players didn't quite "get" how traits and checks work together to give them more options on the "Player Turn". Still, I think we'll all do better next time. And even if we don't it seems like we'll still have a good time.
"If you fudge dice rolls, your system is failing you!" -Sons of Kryos
"I genuinely think that some people measure their free will by reading how unhappy their GM is." - TonyLB