Here’s what I’ve been thinking of doing with Mouse Guard.
1a) A new resolution system. There would still be the contextual matrix of conflict (the basic structure of GM turns and players turns), but what you can do in those turns, and the dice mechanics used would be changed.
1b) A different action table and somewhat different process. Long story short (and I believe I read an old thread about this). Attack has an edge, statistically, in a majority of situations. I have a few ideas to balance it out, and open up the possibility for a larger diversity of actions in conflict.
1c) A different approach to wild (i.e. non-intelligent) animals. Specifically, no more Nature + Nature.
A revamp of weapons and armor.
4a) I’m likely to introduce intelligent snakes. It would really complement what I have planned for magic.
4b) There’s the slight chance I would get rid of Weasels or at least change their species. For what I have in mind, I could see Snakes and Weasels potential working together, but I might be better off either nixing them entirely, or going with another Reptile.
What I’d definitely be keeping:
1a) The players are part of a predominantly apolitical organization striving to ensure the survival of the species.
1b) Mission oriented campaigns. This really works with the GM/Player turn bit.
Cloaks and their symbolism. I really liked that element.
The general structure, culture, and effect of seasons.
Most of the same character elements (Attributes and Skills), and similar character creation method.
My original thought was to do something like Mouse Guard 1325, set far enough into the future to separate it from the original storyline. Considering that a lot can happen in ~175 years, it gives me a big enough window to introduce new elements (and even plot the extinction of the Weasels). If I do that, then it’s still Mouse Guard (the setting), though the system is still going to be quite different. Then again, with all the changes I have in mind, it might be better to consider it as something different than bastardize a perfectly decent system/setting already in place. But, considering I’d still be copping the cloaks and the basic idea of the Guard, is it really much different? I’m not sure. Thoughts?