Games try to give players "moral choices" to be good or evil. But perhaps the most powerful moral system is the one we make ourselves, as demonstrated by a dead goat in King's Quest.
The goat is far from being even a tertiary character in Sierra's King's Quest, and when you meet it you can only do three things: You can feed it a carrot to entice it to follow you, you can ignore it, or you can kill it. There was no point to killing it, there was no consequence or penalty; the game never called you a monster or awarded you dark side points... and yet, every time he did it, Brendan Main still felt bad about it, as he relates in Issue 234 of The Escapist:
There I'd stand, poised at the brink of a syntactic abyss. And maybe I couldn't "take stone." OK. Maybe I wasn't able to "get rock." Fine. But you know what I could do? I could "kill goat." It wasn't out of spite; on the contrary, there was nothing malicious about it. I did it simply because I could - or, more accurately, because I couldn't do anything else. Inevitably I would reach a point where all other options were exhausted. It was either "kill goat" or do nothing at all.
Time after time, that brave goat took one for the team, dying for my gaming sins. Immediately I'd feel terrible. After all, I'd reason, it would still be alive if I was only a little better at the game. I'd resolve to swear off the sordid business of capricide altogether. Telling myself that this time would be different, I'd start a new game, pick a new carrot and introduce myself to another doomed goat.
Perhaps the goat's irrelevance in the grand scheme of things was precisely what made it so powerful. It was your choice, and yours alone - and not forced upon you, either. To read more, check out "Kill Billy" by Brendan Main in Issue 234 of The Escapist.