This is a cross-game modification system which randomizes different games, then uses the result to build a single unified multi-player game. Items from one game may be present in another, and you will need your fellow players to find items you need in their games to help you complete your own.
This is only loosely related to your post but I just came across this project:
https://archipelago.gg/
It supports a whole shitload of games: https://archipelago.gg/games
I only just started reading about it. So far it seems like insanity.