Which Assassin's Creed game is set mainly in Constantinople and follows Altaïr and Ezio?

Assassin's Creed: Revelations is set mainly in Constantinople and follows both Altaïr Ibn-La'Ahad and Ezio Auditore. Ezio travels to the Ottoman capital to recover keys connected to Altaïr's legacy and the Masyaf fortress.

The game was released in 2011 and is the fourth major installment in the original Assassin's Creed storyline. Its Constantinople districts include Galata, Constantine, Bayezid, and Imperial, reflecting the city's importance at the start of the 16th century.

Revelations uses memories within memories to connect Ezio's experiences with Altaïr's later life. It also concludes Ezio's main story and advances Desmond's modern-day narrative.

Constantinople is the historical name commonly used in the game, although the city had been called Istanbul in official Ottoman usage for centuries by that period. The game's setting is therefore sometimes described simply as Istanbul.