Originally Posted by soundlessb00m
I am getting this game tomorrow, how does this work? Do I need to complete the game first?
I host a private game using my Hardcore campaign save and invite you in. Once it launches, the ending plays, and then the credit roll. The achievement unlocks at the credits. You must first complete the campaign on any difficulty, or it won't work.
The campaign save launches straight into the ending video instead of giving you the mission select screen. I think the glitch is the result of the programmers putting the unlock trigger in the credits rather than the mission results screen.