Originally Posted by MaddogMonty
Does it take one consecutive playthrough for the difficulty achievements or can I just obtain them using mission replay / playing levels with people who already have them unlocked?
If you mission replay it deletes your progess and after you complete the mission it puts you back on the streets with every mission active except for the one you just beat. I would just play a whole new campaign personally just to be on the safe side. I dont see anything wrong with replaying but I think that it might be stupid and not give it to you. I would say just wait and see if anyone posts that they unlocked their achievement in that way.