It appears that some copies of Black Ops 2 for PC have shipped with Mass Effect 2 in the place of that game’s second disc.

Gamers on Reddit, the Black Ops 2 Steam forum, and the Call of Duty forum have reported that they are unable to complete installation of the game as a result.

There is no doubt Activision will be fuming over the mix-up – Mass Effect developer BioWare is a division of arch-rival EA.

Gameplanet has contacted Activision for comment.