Which Assassin's Creed game follows Altaïr Ibn-La'Ahad during the Third Crusade?

Assassin's Creed follows Altaïr Ibn-La'Ahad during the Third Crusade. Altaïr is the playable Assassin in the original 2007 game, whose historical storyline is set mainly in the Levant during the late twelfth century.

The campaign sends Altaïr to three major cities: Jerusalem, Acre, and Damascus. He receives missions from the Assassin bureau and investigates targets connected to the conflict between the Assassins and Templars. The story uses a fictionalized version of the Crusades rather than presenting a complete historical chronicle.

Altaïr should not be confused with Ezio Auditore, the Renaissance protagonist of Assassin's Creed II, Brotherhood, and Revelations. Nor is the game the same as Assassin's Creed Mirage, which later depicts Basim Ibn Ishaq before his career as a major Assassin. The original title established the franchise's recurring historical-versus-modern narrative structure.