Mouse Guard is a series of graphic novels from David Petersen about mice struggling and prospering in dangerous Medieval times (sans humans). Think Redwall, I guess.

Rumors abound about a Mouse Guard board game include a supposed source (linked from David Petersen’s blog) of information returns an error, while an audio file follows a reading of the rules and session of the game.

In any case, you can definitely pick up the Mouse Guard Roleplaying Game. Players form their own Mouse Guard patrol and attempt to complete missions while the Game Master takes on the roles of the weather, animals and the wilderness all trying to thwart the fearless mice. (source)