The Revolutions mod add a stability value to each city, based on global happiness and your relation with each culture groups in that city.
The Cultural Diffusion mod is required to calculate stability, and the Custom Advanced Setup Screen is required to reserve CS for revolutions. All mods are also available in the Revolution Modpack collection on Steam workshop.
"Culture" in this mod is not the same "Culture" that allows the player to unlock social policies. The "culture" from the mod is spreading from cities (based on the city output from buildings/wonders) and "mark" the surrounding land, raising in value each turn if close enough from the city or other plots with higher culture value.
Neighbors civs have their culture mixed on some plots, and during wars the conquered land is still marked by the culture of the previous civ (even if values can be lowered/converted to new culture when a city is conquered)
Cities that are away from the Capital will create separatists. The allowed distance from capital raise with each new era and when the city is connected to the capital by road or harbor (but roads are better). Separatists create unrest faster than normal citizen.
Unrest raise faster in conquered cities until a Courthouse is build, and raise slower in puppet cities.
Revolt (city enter resistance), Rebellion (rebels unit spawning nearby) and Revolution (city flipping to rebel faction) can occurs if a city unrest is too high.
Cities in Revolution can decide to join another Civilization after a few turns, or create a new City State (check the option in the setup screen)
Revolutions (v.9) 2016-10-05