Which Assassin's Creed game introduced cooperative multiplayer missions for up to four players?

Assassin's Creed Unity introduced cooperative multiplayer missions for up to four players.

Released in 2014, Unity lets players control versions of Arno Dorian while completing dedicated missions with other human players. These activities are separate from the main single-player campaign but use the same Paris setting, stealth systems, combat, and parkour mechanics. Players can coordinate approaches, distract guards, and perform synchronized actions.

The game is set during the French Revolution and follows Arno's involvement with the Parisian Assassin Brotherhood. Its multiplayer design was a major change from earlier entries, which had experimented with competitive online modes or limited multiplayer features rather than four-player cooperative story missions.

Cooperative missions are not the same as Unity's single-player campaign, and they do not make the whole game permanently multiplayer. Players can complete the main story alone, while the co-op content provides additional missions and challenges. Unity also introduced shared-world activities such as heists, which support the game's broader emphasis on teamwork in revolutionary Paris.