This is purely hypothetical, just for fun. In this scenario, you don’t get to know who the GM is in advance, but they do have to run it as written. The players can leave whenever they like, but the GM has to stay until either all players leave or the players beat the dungeon.
Every room is a menagerie of different homebrew monsters and the stat blocks are page inserts throughout the module book. There is no order. The index doesn’t have a list of monsters. Get ready to hear “Okay, one second…” every minute or so with wildly flipping pages from the GM.
So simple, so elegant. And you could probably name the stat blocks something confusing to make the GM start reading the wrong one.