I wonder if it would make sense to develop a naval war feature? I’m imagining that you could add a shipyard and a sea fort to guard the harbor, and maybe a sea wall with towers/turrets connected to the land. Then you could attack from the sea and bombard buildings. Not sure if it would be worthwhile though. They would probably have to adjust a few things to make it a rewarding development, such as having the naval troop count separate from the rest, and not allowing attackers to drop troops on the shore side of the base unless they are deployed by a ship. There would probably also have to be some kind of offensive bonus for troops attacking from the sea, or a bonus for the defender if troops attack them from the land, otherwise the naval aspect probably wouldn’t be worthwhile.