Incidentally, I'd be rather upset if Byzantium is in the game because doing so would be incredibly historically ignorant. Byzantium was PART of Roman civilization. In fact, throughout their entire history, the people we call the Byzantines called themselves "Romans" and their empire "the Roman Empire." Their law was Roman. They controlled large portions of what the classical Roman empire did (including large chunks of Italy). The empire used Latin until the 7th Century (but a change of language hardly suggests a change of civilization). And, to the extent that the empire was NOT part of Roman civilization, it was Greek.
Similarly, while Austria-Hungary had an Empire, Austria and Germany are fundamentally part of the same civilization: German. They share the same language, culture, religions etc.