Some gamers who purchased a retail copy of the PC version of Call of Duty: Black Ops II have been unable to complete installation because the second disk is not Treyarch's shooter. Rather, it is rival Electronic Arts' 2010 role-playing game Mass Effect 2.
The issue has been reported by users on the official Call of Duty and Steam forums, as well as from gamers on Reddit. The cause of the error is unclear, though it appears to be related to a mistake made on the game's production line.
Representatives from Activision and Electronic Arts were not immediately available for comment.
Call of Duty: Black Ops II launched today for Xbox 360, PlayStation 3, and PC. It is a sequel to 2010's original Black Ops, which is the best-selling series entry to date, moving more than 25 million copies as of August 2011. A Wii U release will follow day-and-date with the system on November 18, with a PlayStation Vita game Black Ops Declassified also shipping November 13.