Video games can elicit a feeling of empathy for the characters, even though the player knows perfectly well that they are fictional, and nothing more than some leds on a flat surface lighting up with different colors, and some pre-recorded sounds spoken by actors. Willing suspension of disbelief and all that.
I myself find it really hard to commit atrocities against innocent people who have done nothing wrong in video games.
For example in
Fable, you can accept good and evil quests from a guild. And the evil quests really are evil. They consist of things like massacring an entire village of people who have done nothing wrong. And while you are massacring them, the NPCs you are killing will cry "why are you doing this?" and such.
Do you know what's even more evil? The fact that once you have accepted a quest, you can't cancel it. It will be in your list of active quests forever, and can't be removed. What's worse, the quest list doesn't make it clear at all which quests are good and which are evil. There simply is no indication. You just have to deduce from what the quest description entails.
At one point I mistakenly accepted such an evil quest, an only realized much later that it was one. I was stuck with it, even though I didn't want to do it.
Fine, just don't do it. Keep postponing it forever. Right? Wrong. The quest consisted of massacring a village, going through said village was mandatory to advance in the main quest, and the evil quest triggers automatically when you enter the village. You can't avoid it. You can exit the village, but that doesn't help; the next time you enter the village the quest triggers again. And you can't go through the village without killing everybody.
There was no way to cancel the quest and I didn't have a save from before accepting the quest. I was stuck. The game had effectively "soft-locked" on me because I couldn't do the quest.