Which Assassin's Creed game was the first in the main series to feature four-player cooperative missions?

Assassin's Creed Unity was the first main-series Assassin's Creed game to feature four-player cooperative missions.

Released in 2014, Unity added cooperative missions that allowed up to four players to work together online. These missions used the game's Paris setting and emphasized coordinated stealth, combat, and movement. Players could customize Arno's equipment and abilities while tackling shared objectives.

Earlier games included multiplayer or connected features, but they did not provide the same four-player cooperative campaign-mission structure. Assassin's Creed Brotherhood and Revelations are especially easy to confuse with Unity because both include multiplayer modes, but those modes were primarily competitive rather than four-player cooperative story missions.

Assassin's Creed Unity remains distinct within the franchise for making cooperative play a prominent feature alongside its solo campaign. Its historical setting is Paris during the French Revolution, and Arno Dorian is its principal protagonist.