I made a 1-page megadungeon in 2017 that was 5-dimensional and weird enough that the players eventually became more afraid of the rooms that appeared empty than the ones filled with flames or completely full of corpses or horrifying monsters.
I also co-made a dungeon that was a full-sized ruined dwarven metropolis complete with a magical subway system run by a goblin cult, a section overrun by magma elementals, and sewers filled with symbiotic mycelium that produced the city's food in exchange for waste and bodies.