Assassin's Creed Revelations is a third-person action-adventure stealth game set primarily in Constantinople during the rise of the Ottoman Empire. Players control an aging Ezio Auditore as he searches for five keys to unlock a library built by Altair, while also playing brief flashback sequences as Altair and first-person platforming sections as Desmond Miles. Gameplay retains the series' mix of combat, climbing, and stealth, adding a hookblade for faster traversal and zipline access, a bomb crafting system, and a tower defense minigame. The multiplayer mode from Brotherhood returns with expanded maps, characters, and modes.

In 1511, the aging Master Assassin Ezio Auditore da Firenze travels to the fortress of Masyaf, the former stronghold of the Assassin Brotherhood, seeking a library sealed away by the legendary Altair centuries earlier. He finds the fortress occupied by Templars, who attempt to execute him. Escaping, Ezio discovers that Altair locked the library with five keys and hidden them in Constantinople. Ezio journeys to the Ottoman capital, where he befriends the local Assassin leader Yusuf Tazim and a young prince named Suleiman. He also meets Sofia Sartor, an Italian bookshop owner, and together they follow the trail of the hidden keys. Meanwhile, a civil war brews between the Ottoman princes Ahmet and Selim over the Sultanate, and a faction of Byzantine Templars is exploiting the chaos, raising an army to overthrow the Ottomans and reclaim the city. Ezio must unravel this conspiracy while racing to recover the keys before the Templars do.