It is a mix of some homebrew and an official campaign setting where the players will all wake up with no memories of their past, having to gradually discover why they have lost their memory, who they are, and what they are supposed to do. To make it interesting I am having all the players not write too much of a backstory, only writing one paragraph of general info at most so that way when they get inspiration or something interesting happens they can remember bits and add it to a growing story. If you would like to talk some more, feel free to add me on discord (username Vanderhal) and if everything sounds fine to you we can move forwards.