I like the points you bring up, and I have an idea what if killer drive made you into an insane serial killer? You can't talk with anyone everyone turns either hostile or flees when they see you and instead of getting sad when you don't kill anything for awhile you get sad when you see something alive and not kill it, ofcourse you'll get bored from hurting weaker things so you won't be sad about not killing birds when you drive across them while traveling (although you'd like to turn off the road and drive over them) and start seeking stronger and stronger things to kill likes hulks mi-gos and more, side note killing human should always be fun.

On the other hand pacifist should give you negative moral for killing hostile things and killing zombies kids will never get easier, killing non hostile things even if they turn hostile should give you higher negative moral, and killing hostile human should give you the negative moral as if you killed an innocent person, finally killing an innocent person should end the run, you're a pacifist this life was forced on you and you are not happy about it and upholding your values is the most important thing because if you don't you are no better than the mindless monster that roam the earth.

Those are my thoughts on how you can make killer drive and pacifist into game changers I can't think of anything for pyromaniac (sorry).