I'm attempting to complete the whole game unspotted and no kills for achievement purposes. I don't understand how the don't-kill-anyone achievement works. I was told I can make people commit suicide, but I don't know how. How do I do it?
Check this source: http://dishonored.wikia.com/wiki/Harm's_Way
Easiest way to do it is to use the posession skill.
Possess a person and walk towards a wall of light. Right in front of the wall end the possession, the person will continue to walk a bit further and will therefore kill themself in the wall.
More complicated way would be to bring a person in front of their own projectile when they are shooting at you. When they shoot, stop the time + possess the person, walk in front of the projectile and end the possession. As soon as the time continues they will be killed by their own projectile.