The only in-game objective is to obtain as many prestige and piety points as possible in order to surpass the various historically relevant European dynasties in a fictional prestige ranking system (the three most prestigious ones being the Capetian, the Rurikid and the Habsburg dynasties). The game depicts or mentions numerous historical figures, including William the Conqueror, Charlemagne, Genghis Khan, Harold Godwinson, Robert Guiscard, Robert the Bruce, Harald Hardrada, El Cid, Constantine X Doukas, Harun al-Rashid, Alexios I Komnenos, Richard the Lionheart, Ivar the Boneless, Alfred the Great, Baldwin I of Jerusalem, Boleslaw the Bold and Saladin, but allows for the player to choose less-significant figures such as minor dukes and counts, and for the creation of entirely new characters with the use of the Ruler Designer DLC. Through the strategic use of war, marriages and assassinations, among many other things, the player works to achieve success for their dynasty. Players are able to start at any date between January 1, 1066, and December 31, 1337, though the Old Gods and Charlemagne DLCs allow for earlier start dates of 867 and 769 respectively, and the Iron Century update allows a start in the year 936.

The game is a dynasty simulator in which the player controls a medieval dynasty from 1066 to 1452.

Crusader kings 2 middle earth project