Europa Universalis IV: Cossacks [Download]
Estates: Adds internal politics in your country, with power groupings such as the Church, Nobility and Bourgeois fighting for control.Diplomatic Feedback: Adds the ability to interact much more deeply with the AI by setting your attitude and telling it what you want out of wars.Tengri: New religion mechanics focusing on Syncretism. Tengri have a secondary religion that they fully tolerate, and can change this secondary religion at will.