Culture spread from cities, each tile can host culture from multiple civilizations. You can still buy tiles, but they can flip to another Civilization if it has more culture than you on it.
Culture spread automatically from cities in all directions, is slowed by crossing rivers or mountain and accelerate following river or road. Once a civ reach a threshold value on a tile, it will flip to that civ, if it's the one with the higher percentage of culture.
Introduced in v.7, military units can capture tiles, temporary (15 turns) if there's no trace of the unit culture on it, or until they flip back from culture ratio.
- download the civ5mod file to your mod folder (..\My Documents\My Games\Sid Meier's Civilization 5\MODS).
- launch civ5, go to the mod browser and click "install mod"
- find the "Cultural Diffusion" line and activate the mod.
- from the mod section, go to single player and set up a game
Credit & thanx
Whys (SaveUtils) and a lots of people here
- Reflect Great Artist culture bombing on culture map
- City flipping from culture (or not)
Cultural Diffusion (v.18) 2016-10-05
Cultural Diffusion (v.18)