With the release of Assassin's Creed Brotherhood coming up within the next few months, Ubisoft has now officially announced a new game in the series that'll be released exclusively on Facebook.
Assassin's Creed's "project Legacy" will be a social role-playing game where by completing and unlocking certain missions, you are then able to unlock more missions in "Brotherhood". Also, depending on the tasks you complete in "Brotherhood", you are then able to unlock more missions in "Legacy".
Players should expect about 25 exclusive missions in "Legacy".
There's no official announcement on when the game will be released, however, Brotherhood will be out in stores November 16th for the PS3 and XBox 360.