The specifics haven’t been revealed yet, but we do know that, if you follow a certain event change when playing as Charlemagne, you can indeed-with a bit of luck-essentially recreate his great deeds. Much of the gameplay of the new expansion seems like it’s focused on various series of events that can lead to the Empire’s formation, either in its familiar form or a rather different one. The most obvious is that, at that very early date, the Holy Roman Empire, generally the dominant power in Crusader Kings 2, does not yet exist.
And that early date brings a whole slew of new events, features, and other changes. The Glory of Charlemagne release date focuses on Europe-looks like Rajas of India was a one-off-and extends the game’s earliest possible start date to the 8th century, during the rise of a certain Charlemagne, future founder of the Holy Roman Empire.