The Charlemagne Add-on for Crusader Kings II has 13 achievements.
Play a game all the way through from 769 to 1453
Be King of Frisia and hold the Atlantic coast from Léon in Brittany to Jylland
Play as a Tribal Ruler and Reform to Feudalism
Found the Holy Roman Empire in a game starting in 769
Rule as Emperor with the Reformed Zun Faith
As a Christian non-Saxon, completely conquer Saxony in a game starting in 769
As an Anglo-Saxon or Saxon ruler, be king of both Saxony and England
Become Emperor of Francia as Carloman, brother of Charlemagne
Hold any Emperor or King title as a Lombard after 1300
Have a capital province with Norse culture and Muslim religion
Be simultaneously at war with the Aztecs and the Mongols
Divorce a Lombard Princess as a Christian
Play as a Tribal Ruler and Reform to Merchant Republic