Ubisoft is requiring an online pass from users hoping to access part of the single player campaign in Assassin's Creed 4: Black Flag, GameInformer reports.
Players will need a Uplay Passport, the game-specific code attached to new copies of the game, before being able to access Black Flag's fleet system which allows protagonist Edward Kenway to add ships to his fleet and send them on missions to return with money and rewards.
Similar systems were previously made available as offline features in the series, including the assassin recruitment feature in Assassin's Creed: Brotherhood. In Black Flag, however, players can have friends assist them in order to make missions go faster, although it isn't necessary for these missions.
Assassin's Creed 4: Black Flag launched on Xbox 360 and PlayStation 3 this week. The game will come later to Windows PC, PlayStation 4, Wii U and Xbox One.
We've contacted Ubisoft for further information and will update when more details become available.