Crusader Kings II is a grand strategy game set in the Middle Ages, developed by Paradox Development Studio and published by Paradox Interactive as a sequel to Crusader Kings. It was released for Microsoft Windows on February 14, 2012. An OS X version, Paradox Interactive's first in-house development for the operating system, was released on May 24, 2012. A Linux version was also released on January 14, 2013. Since being released, it has sold over 1 million copies, which made it Paradox's most successful release before the release of Europa Universalis IV in August 2013. A sequel, Crusader Kings III, is set to release in 2020.
The game is a dynasty simulator where the player controls a Medieval dynasty from 1066 to 1337, though the DLC The Old Gods and Charlemagne allow for earlier start dates of 867 and 769, respectively along with 936 due to the Iron Century update. Through the strategic use of war, marriages and assassinations among many other things, the player works to achieve success for their dynasty. The game contains numerous historical figures such as 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, and Saladin, but allows for the player to choose less significant figures such as minor dukes and counts, and creation of entirely new characters with the use of the "Ruler Designer" DLC.