Gang Guard (channeling old TSR titles)… but we’ll explicitly use the Chicago of Al Capone & Eliot Ness.
Les Grandes Sourix (yea, horrible French)… Formula 1 racing! Replace Fighter with Racer.
Did we get Gamma Mouse yet? Very nearly the same game as Mouse Guard, but with much weirder animals, weather, and locations.
Mousequerade: The game of elegant refined mice in an 18th Century Manor House.
Mouse: The Sqeaking
Mouse Busters
Mousehole Impossible
Miami Mice
The Once and Future Mouse
Kitchen Stadium Guard (Iron Chef!)
The Good, the Bad, and the Mousely. Spaghetti Westerns.
Ride with the Mouse. The Border War between Kansas & Missouri.
Crouching Mouse, Hidden Weasel. Relationship-driven wushu!
Mouseback Mountain. Just to continue the Ang Lee thing. 
An American Civil War game actually seems more appealing than a straight up Western. The Border War is more do-able because it tended to be less about armies and more about cavalry raiders & irregulars.
I might peek at PIG’s Revolutionary War thing as well (for their Coyote Trails game)… So, “The Purfuit of Mousinefs”?
(Wasteland/Fallout is better than Gamma World IMO.)
To Boldly Go Where No Mouse Has Gone Before would be easy to do. Far easier than Star Wars. Take a little bit of Omnihedron’s Duty & Honour, plus Trek crap, plus MG-style conflict resolution. Easy!
We named the Mouse “Indiana”!. Indiana Jones or Lara Croft kind of fighting-archeologist adventure thing against the Nazis. The cover of the latest Game Informer with the new Lara Croft kind of inspired me. Dirty, dirty girl.
Achtung Mousetang!. WW2 flying aces. OR, maybe tank commanders in Western Europe (mainly Patton & US Shermans). See, this is what my (uparmored) Mouse Guard book looks like (in the bathroom of a suite at the Doubletree, Foggy Bottom, DC). The back cover is protected by a sheet of cardboard:
