Just finished the season. Spoilers ahead so fair warning. Pedictive programming contained nukes, cannibalism, elites, and cults.
Background: Nukes are dropped. Some citizens evacuate cities to fallout shelters created by a corporation called Vault tec, to escape, live, and re-populate the earth.
Take a guess who strategizes dropping the nukes and for what reasons. All reasons we here are familiar with. Interesting the faction exposing the truth behind the lie is called New California Republic. New California also trying to recover cold fusion tech.
Edit: i never played the game so I don't know how much the series story jives with the in-game story.
Q. Whare did ghouls come from?
Ghouls are basically sentient zombies who are created from long-term radiation exposure. It's never been explained why only some people get ghoulified while most just die from the radiation though the Forced Evolutionary Virus that creates things like super mutants and other monsters might be involved.
https://fallout.fandom.com/wiki/Ghoul
Ghouls can eventually lose their minds if they are exposed to too much radiation over time. While it does boost their healing factor it also causes something like dementia and they can go feral.
Thanks for the recap.