I watched an developer interview recently that said in the game Dishonoured you can get through the whole game without killing anyone.
It's curious these games that have options like these - yet what is the advertising? Shiv to the neck! Shiv to the neck! Shiv to the neck!
I'd assumed (call me assuming) that it was another murder porn game that secondarily has some strategy element. Now I'm not sure what design philosophy the developers have.