Ah, child killing video games.
Enter Richard Garriott. You know, this guy:
He made the Ultima series!
And in several games in said series, you are actually *forced* to kill one or several children. This can include dropping them into a pit of lava, killing a giant group of child soldiers, having a random-ass child mage in a world where magic doesn't work start throwing fireballs at you, opening a cage allowing a large group of monsters to eat a group of children...
And, of course, Garriott did all this simply because he received letters from his family telling him not to do it during the creation of the series.
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Actually, you're not forced to. During his interview with Spoony, he points out that there's multiple solutions to the problem that don't involve killing: running away, casting Charm, Sleep, Paralyze, or Fear on them. You had options. Just goes to show how many RPG players automatically see an enemy and decide to just kill them, instead of finding an alternate solution to the problem.
Also, killing children is one of those things that's been taboo ever since a bunch of moral guardians pissed and moaned about the "horrible violence in games turning our kiddles into trained murderers." Wasn't too long after that when children all but disappeared from games and, if they
were present, they were conspicuously immortal. Think of it like this: with children that could come to real, actual harm, gamers could be forced to think about their choice of attacks and approach far more effectively than just random adult NPCs. Protecting kids is an instinct most of us have. With mortal kids, you now have to look out and think "should I use this fireball of apocalyptic power or not?" It gives their presence weight and gravitas that is missing when they're either simply not there or immortal. I sure as hell know that
I stopped using the minigun in Fallout whenever kids might be in the line of fire. Besides, look me in the eye and tell me you haven't wanted to punch some of the little shits you come across (like in Skyrim) just once and have it actually
do something.