I have been searching for years for a good realm-management rule set for RPGs. By "realm management," I mean a system that tracks the fortunes of large areas and / or groups in the way that most RPGs track the fortunes of individuals.
For example - A fighter grows rich enough to build himself a motte-and-bailey stronghold. A realm management system will tell players when his buildings need repair, when his holders are hungry, when his neighbors are making war on him.
I am currently happiest with the rules from Reign but I know it's far from perfect.
I would like to know what realm management systems rpg.se users like and use.
UPDATE: I eventually chose the answer with Reign, but I'm still not quite happy. Aramis, thanks for reminding me about the older Pendragon systems. I'm hoping to find additional goodness in Fief and Town both from Cumberland Games.