From Jonathan Trevisani’s CGOnline review of Medieval II: Total War:

The Holy Roman Empire (also known as the Byzantine Empire) was the empire of my choice so I could teach all of these hooligan fiefdoms the glory that was Rome could once again rise.

It’s stuff like this that gets me frustrated with the state of modern education. This is the type of thing you can easily look up if you’re unsure, and if you were sure, you’d never make this mistake. The HRE and Byzantine Empires were not the same. In fact, both are separate nations in the game, which you would know if you had played through a campaign and unlocked the Byzantines, looked at the custom battle setup where you can match any armies against each other or even marched your Holy Roman army just a little bit southeast.

In other words, the type of error you wouldn’t make if you paid attention while you were playing.