hunterIV said:When I first loaded up MCC on Steam, I unlocked 300 achievements from my XBL progress and was missing a good number of them. This was in July. I just loaded up the game again and unlocked another 99. I am still missing 65. Is there a method to get the rest of the achievements to cross over?
Halo 3 ODST is a recent addition to steam (week or so I believe) so looks like some retroactive unlocks. Halo 4 is yet to be added and is marked as coming soon.
You haven't linked accounts so I can't check but if the remaining achievements are Halo 4 I think we have our answer.