Everybody disappears and returns 1 by 1 every second
Actually an idea for series of books and stories. Everyone gets send to some kind of purgatory, where no one ages, people can't touch each other, can't harm anybody and themselves physically, but can talk to each other and get pen and paper for whatever that returns with them. the place itself is endless empty plane, if you look up you see what year it is in a way that you are used to. And every second (or even every couple seconds) one person returns to the real world. The stories are following different people, some are first returners and it is more of a post apoc (cities with population of a million will get on average a person every ~2 hours), some return in a thousand years and it is more of a science fiction (something like futurama, but the people weren't hibernated like Fry), some are late returners and we don't actually follow their return. but the way they leave in the purgatory. And the people in there will with time divide into different groups, like here you have physics theorists that push the fantasy of how far can we push our understanding of the world without any new information, here you have extreme psychology researchers (kinda like unit 731) that exist because psychological torment and experiments can't be stopped by others.
Just got this idea and it seems fascinating to me, but I'm not sure if it would be that interesting, would like to hear your opinion.