My save game got corrupted somehow in year 1262. I can play, but the game crashes as soon as the game tries to save. Which is a shame, I was on my way to "world" domination! I had a weak claim on the crumbling Kingdom of Aquitaine on the line, and while the HRE and Byzantium could both muster more troops than I could on a good day (70,000 and 60,000 to my 50,000 and the HRE had infinite money), it wasn't among my plans to attack them "on a good day". A sad moment for me, I had 70 hours into this game.
Screenshot (I am the Empire of Alba; note Jerusalem and bits of Lithuania).
EDIT: Short description of the game: I started as the Duke of Munster (two counties in Southern Ireland, recommended for your first game), slowly conquered all the independent counts and dukes of Ireland and became king.
I managed to marry the heiress to the Kingdom of Scotland, but the damn scots usurped the throne from whoever. I had to fight them three times to get control over the throne (two of my -young- claimants died as I was finishing their respective wars, talk about bad luck).
I invaded Wales county by county with fabricated claims. That was boring.
I managed to marry a distant relative to a female claimant of the English throne. When they got babies, I put that guy on the throne, and spent two decades or so killing rebels for him. Then I married his heir to my heir and got tons of inbred babies, which were quite costly to get rid off so that the non-inbred actually became my heir.
Brittany I got because there was nothing going on for a while.
I got Jerusalem from the second crusade. Defending it was difficult, but luckily the Templars were up to the task; but getting all my armies there everytime some Muslim got funny ideas was kinda annoying. I got bits of Andalus in the Third Crusade, and stole other bits from the Castilians; that was difficult, because every-frickin-body in the Peninsula are relatives, so I basically had to declare war on all of them at the same time. I got Lithuania from the fourth crusade completely by accident, I was there only to get the crusader trait on my emperor and his vassals, and then poof, I am the king of Lithuania. At least the region is stable.