It might be fun to add NPC raiders - like zombies, but with weapons and different tactics. Maybe even a random engineer or two to mess with traps. Best of all, if you kill them, you have a chance to get loot.
Bug: sometimes the "go" button shows up in place of fight. Pressed it while trying to conquer a town - ended up going on without actually missing the map.
How can you shoot lightning out of your hands or raise demons from another world?