Who doesn't love a game where you can kill innocent bystanders in?
First game I played that you could do this is Mission Impossible for N64 and I was pretty shocked that I was able to kill someone who wasn't going to fight back. I think you only had 1 bullet or something though but I was really scared actually that I killed someone who was "good"
Other games was The World Is Not Enough for N64. I remember the people in the game would actually fall and then try to crawl away but die shortly after.
There's a few more I can think of, but I didn't play them until recently.
What I've got so far
Blackthorn
Flashback
Mission Impossible
World Is Not Enough
Fallout
Help my list out :]