From publisher blurb:
Chimneyhaus is a "sword and whiskers setting" for Isaac Williams' excellent OSR-style game, Mausritter. If you haven't played it before, we highly recommend checking it out!
Chimneyhaus includes the settlement known as Chimneyhaus, built, obviously enough, inside a chimney on an old dairy farm. From there the mice make cheese and brew mead and try to survive in a world full of cats and other terrifying (to mice) creatures.
Beyond the settlement is McRheetz Farm, a fully detailed adventure site, with adventure hooks ready to get your party into the action. And beyond that lies County Langlade, a place of magic and mystery, as well as the many factions that vie for power there.
In this setting, we've also created new spells, conditions, and creatures for use in any Mausritter game.