Gnawnia
Gnawnia is the first area you go to. No map pieces are required to unlock this area or any of the locations in it. You simply have to rank up to unlock the next location.
Meadow
The very first location you start at. The mice here aren't particularly strong and are all indigenous mice (except for pirate) that are affected by all power types except parental.
Town of Gnawnia
The second location you travel to. The mice found here are similar to the mice found in the meadow and are affected by all power types except parental.
Windmill
This is the next locations beginners travel to. The mice found here are affected by all power types except parental.
Harbour
This is the last location of the first linear part of Mousehunt. Beyond here, you have two choices. The mice here are all affected by all power types (except for pirate) except parental.
Mountain
This is the last location a hunter can access to in Gnawnia for a while. The mice here are affected by all power types except parental.