I played through every mission and all my stats say I didn't kill anyone on any of them. A few said bodies were discovered but the achievement only says "complete the game without killing anyone." Which I did. I didn't do any of the granny missions. I replayed all the missions individually so I wouldn't kill anyone. Do I have to actually go through the whole last mission for the achievement to think I completed the game?
There is a bug with Granny Rags. When you get the sewer key from her Slackjaw will tell you to burn her cameo so she can be killed. After destroying it any action against her, even knocking her out or sleep darting her, will count as a kill. The mission report will still say you didn't kill anyone but it will cost you the achievement. Annoying but that's the way it is.
Yeah I completely avoided all granny rags missions. So when I did the mission where she's supposed to attack and I'm supposed to get the key I never had the option of doing it because I never met her. So shouldn't it work then?
If it's not the Granny Rags glitch then I don't know what it is. Maybe there is a similar bug with another character? Perhaps with Havlock at the very end? It feels like a similar situation. Did you knock out the backstabber? I think someone once said to just grab the key off the table near Havlock and quickly release Emily. Stop Time helps with this. Give it a try.
Sad to say, but it was probably the Assassins in the prologue. When fighting them, do NOT attack- just block.
What.... WHAT?... that's ******* bull****.
Someone on the 360 achievements site said it doesn't though, so I hope he is right.
What bugs me about that though, is that you are thrown right into the action, and since it is the beginning of the game, your initial reaction would be to fight back. Not to mention that it doesn't effect the other no kill achievements.