Quick thing about a guide

[Ciaran]

You can't change a faction's culture. Culture is hardcoded.

You could rename every single thing in the files between two factions, thereby "swapping" their cultures.

It wouldn´t really swap their cultures, just their looks, you´d still get cultural penalties.

If you wanted a fifth Roman faction, for example, you could take Egypt (Egypt is always good, it´s a single-faction culture), give them all the Roman units and buildings and they´ll look Roman. But they won´t get senate missions or share the map recon and they might go to war with the original Roman factions on their own.