If you don't know Undertale, you should play it before reading about it. If you DO know it, you'll understand the following:
My son invited me to play a couple of years ago. Refused to tell me anything, but sat next to me the whole time. As I made choices that increased my LV and EXP I was really proud of myself. I was killing! I was winning! I was learning how to be a gamer!
The end was so hard, but I won! Only to realize that I had made a terrible mistake.
The world was worse for me having been there, having killed and been so violent. I had made horrible choices all along the way to kill and hurt, because I thought that's what you did in games like this.
My son questioned me - a lot. Why do you want to kill things, Mom? Every once in a while he would chuckle to himself. At the end he said he was really surprised that someone who taught peace could be so harsh.
He taught me great lessons about myself and my assumptions & I just love him for it.
@ashleymcguire thanks for sharing, that is wonderful. Stories like that are why I love gaming in general (tabletop and video).