Initially I planned on just going through the game and playing it by ear. Unfortunately my completionist side took over. I just finishedthe first real mission both without getting seen (tho for some reason achievement didn't pop up) and without killing anyone. This kind of made me want to do the entire game like that. Unfortunately during the prison escape I killed the dude that the tutorial tells you do drop on.
Will going back to that mission and replaying it without kills count towards a no kill playthrough? Or do you have to do it from the start?