Hearts of Iron 4: Battle for the Bosporus — addition for historical real-time strategy. National focus trees will be available in the game for small states on the Black Sea and Aegean coasts. Now Bulgaria, Greece and Türkiye will be able to resist major players trying to conquer the strategically important Bosporus and Dardanelles straits. You can follow the historical path or choose your own.
The add-on requires the original version of Hearts of Iron 4.