Assassin's Creed. No wait...stay with me...My newest savegame is the Super moral Ezio who can't sleep at night if he has to think about orphans and widows. Beating up entire castles full of guards armed with swords is strangely entertaining, especially the aftermath with 30 uniformed men rolling around Ezio clutching their chests and groaning.
Sadly, I am still forced to kill bosses, so let me think...
...possibly 'From Dust' or 'Grand Ages: Rome'. Sure it's possible to kill people in those games, but I try to play without bloodshed. If I can (assuming nobody incurs my wroth)
Admission: These are exceptions to my general rule of killing EVERYTHING in sight. Typically on Assassin's Creed I will think nothing of chasing lute players two miles across rooftops to drive a wristblade into his neck and then dump his twitching corpse in a nearby fountain so that the water will run red as an example to all other bards, beggars, couriers, crazies, guards and general people with disabilities that get in my way!
Now if you'll excuse me, my pacifist gaming evening has built up a healthy appetite for cold hearted killing. **boots up Evil Genius**