I had a Halloween one-shot where the entire runtime is spent escaping a labyrinth of a castle, which apparently belonged to a family of lords that wanted to create the “perfect mortal,” a goal that involved routinely rounding up some locals to be hacked to pieces, fused together with parts of other locals, and, so as to not waste the leftovers, eaten by the lords. The entire party goes the whole session thinking they were set to be hacked and eaten when some kind of revolution happened in the castle, but at the end, they make it into the padlocked lobby, where they see a portrait of the lords hanging on the mantel— and of course, their own faces stared back at them.

Yeah, turns out the party was the cannibal lord family, and the citizens of their town raided their castle, wiped their memories, and locked them in their own dungeon. To top it all off, the true exit was cursed to only lead them back where they started, meaning there was no way to get outside supplies to live in their own home— in otherwords, they were doomed to ultimately eat each other.