How quickly your culture can absorb new people. If you’ve got a hundred people who are in culture a, and you integrate 100 people from culture b. Now culture a is 50/50. And it’s hard for culture a to maintain its traditional positioning.
If you want to maintain a culture, a people, a language, you need to gate how many people enter the population at any time. So that it can be absorbed.
You similar problems with militaries, how quickly they can ramp up new recruits will still maintaining their previous cadre culture.
Sunken City… it just drags on and on and on. I want to finish it, but every time the main mission gets interrupted by a side quest or I can’t find the “trigger” for the obvious next step clue I lose the will to play the game.