How did the world end?
This is one of the core assumptions of Apocalypse World. It’s a simple question that sets the tone for the entire game, but it can also be taken for granted. It’s easy to jump to the conclusion that all AW games are like Fallout or Mad Max, but it doesn’t have to be that way. Nausicaä of the Valley of the Wind is certainly post-apocalyptic, but the different tone makes for a completely different story. Just by changing this one assumption.
So, how did the world end? I’d like to hear some different answers to this question, particularly ones that would lead to vastly different post-apocalyptic scenarios than the default. Science-fantasy apocalypses are especially of interest to me.