I seemed unable to post this in the brainstorming section for some reason, wasn't given the new topic button. Anyways, on to the idea!
Now that we have city building that lets us put buildings away from the settlement, I think that gives us the perfect springboard for another addition I've long wanted and thought would be a cool addition to AVWW. Let the overlord/lieutenants/vengeful ghosts build up invasion forces to attack these non-essential buildings. Perhaps they cannot make it to the settlement proper, that way it would be impossible for them to make a game unwinnable, but they could attack the outlaying buildings, basically disabling them until you clear out the invading force.
They could show up as an invading force on the map, and every X number of days build up, and then will march off to attack one of the buildings. If they get there then you would need to complete a mission to regain functionality of the building. Then there could be mission types for your NPCs, to weaken the invading force, or reclaim buildings.
This could have some very cool potential and make the threat of the Overlord seem like a real proactive baddie instead of just sitting on his tower not really doing anything. And adds a sort of dynamic almost Din's Curse layer to the game. Strategic difficulty could affect how often you'll get attacks (ranging from never, to near-constant raids). And then you could add new buildings with a more defensive role, barricades for instance, or defensive towers that weakens the enemy if they go through it. Or provides defensive buffs if you do a fight off the invading force mission there.
