Assassin's Creed: Revelations is a 2011 action-adventure stealth video game developed and published by Ubisoft. It was released for Xbox 360 and PlayStation 3 in November 2011, and for Microsoft Windows in December 2011. It is the fourth major installment in the Assassin's Creed series, a direct sequel to 2010's Assassin's Creed: Brotherhood, and the final game in the 'Ezio trilogy'. The story is set in an fictional history of real world events set in three time periods, and features three returning protagonists: Altaïr ibn-La'Ahad in 13th century Masyaf, Ezio Auditore da Firenze in 16th century Constantinople, and series protagonist Desmond Miles in 21st century America. The main story follows the Assassin Ezio's journey to unlock the secret of Altaïr's vault in Masyaf using disc-like artifacts containing Altaïr's memories. Intersecting with these historical events are the modern day activities of Desmond, who relives Ezio's memories to find a way to fight against the Assassins' enemies, the Templars, and to prevent the 2012 apocalypse. Assassin's Creed: Revelations is set in an open world and presented from the third-person perspective with a primary focus on using Ezio's, Desmond's, and Altaïr's combat and stealth abilities to eliminate targets and explore the environment. The protagonists are able to freely explore the Assassin's base in Masyaf, and the city of Constantinople to complete side missions away from the primary storyline. The game was followed by Assassin's Creed III in November 2012, a direct sequel that continued the story of Desmond Miles and introduced a new 18th century playable character.