I don't know how dedicated you are to playing the game straightforwardly, but... I've done Darkmoor without killing anything (I played a game trying to kill as few enemies as possible). There are some things you can avoid and shortcuts you can take, and a hidden door. Generally have to set Beacons to do it, but it's doable.
I would note that I've also done Darkmoor killing absolutely every critter in the dungeon.