we had an idea that involved the reworked AI pathfinding
We would identify a series of important blocks in a claimed area, then the AI pathfinding would, from a given outside point, try to plot a path ignoring doors to try to get to the important blocks. Then it would turn them into a Unreal Tournament style Domination style battle, where the opposing force would have to try to take these points, hold them, and by the end of the battle period, it would check how well you did
If there was no path to be found to these attackable points, the fight would instead revert into team deathmatch, and you would be free to demolish the whole castle, because clearly the castle was designed to be untakable. During the battle period, building and repairing would be unavailable in the contested zone.
The idea was that we wanted people to fight over the castles, and design their castles to be more difficult to conquer, rather than just demolish
There were a lot more ideas that expanded further on this concept, but that's the core idea how I would change wars
Both the attacker and defender would negotiate over the time slot
They could pour in resources (resource sink!) to buy favours during the war negotiation