After taking a turn in the secession game I decided to start up my own fort. Two and a half years in, I have seen a weremoose attack (two dead, infected militia commander is trapped in a walled-off section of the fort), and just now an Etten (a giant two-headed humanoid creature). The Etten died without too much disaster, but it has dropped a tablet which turns anyone who reads it into a necromancer.
