Crusader Kings II: Good Job High Chief Piast, 10/10 A+

On the topic of CK2 and gigantic Muslim empires, I thiiink the largest I've seen was a Seljuk empire that stretched from Greece in the west all the way to Persia in the east and (somehow) managed to competently hold it together? The only major crusades to put a dent into them were quickly undone and Christianity was falling apart after a while, as Hungary converted to Catharism and steadily collapsed the moral fabric of the Papacy. It was pretty fun!

I think CK2's got a recurring glitch with pagan coat of arms, as I've heard of that bug happening to other people.