Well, I scanned all of the computer games in and on my game shelf at home, and all of them involve killing in some way. The only half-exceptions are Civilization IV and Space Rangers 2. In Civilization I tend to play a very peaceful game and don't start any wars. In Space Rangers I didn't attack the other trading ships. But, both do still involve killing. Every game on the shelf. I find that strangely funny.
If you leave the shelf for my archives, you can find a couple others that don't involve killing, or at least it isn't a primary focus: SimCity 2000 and 3000, two Monkey Island adventure games, Worms Blast, and the whole You Don't Know Jack series. Pretty much everything else in there, probably over a hundred games, involves killing other people, and for many of the games, that's a primary focus.