Add some new costs of war, for example: Distabilization Enemy's Economic and Politics on few turns when you capture (or destroy) enemy's Capital Star System (CSS).

For example: When you Capture enemy's CSS, in Colonies slowing Building Structures and Discoveries (2 or 4 turns); also, colonisation processes stop (4 turns) and Migration (Evacuation) processes stops too.

And more: move Capital to other SS doing during few turns (3 or 4).


BUT: Enemy (or You) can study appropriate technology in Tree.