I did Ghost (think thats whats its called, no kill, no alert) bonus for last 80% of the human revolution game. Only reason not 100% is I didn't know of this until a bit later.
One of the few games that actually reward avioding killing and avoiding enemies. Its a true sandboy game, & so many ways to achieve same targets. Upgarde that matters & change the way you play & open up options. & the ending....