Nightmare Fuel / Dragon Quest Builders 2

• The moment where the penny drops, the Wham Episode: At the climax of the Moonbrooke chapter, the Builder and company happen upon a total area shift, leading to Middenhall castle... which shouldn't be there. Your way in is surrounded by monsters who are unsettlingly serenely commenting on how their reality is a lie, and how they and everything else will be destroyed soon. At the depth of the castle in the throne room, the King greets the Builder incorrectly as the Prince of Middenhall...and then begins to violently glitch out and vanish with everyone else. This culminates in the realization that this world and everything in it is an illusion.
• The Lotus-Eater Machine sequence Malroth suffers after Hargon abducts him to induce a lovely bit of Mind Rape and cause him to cascade into the bonafide God of Destruction. Specifically, a black void where Malroth is accosted by skeletons, only to look back behind him and see a literal sea of blood with all his friends' corpses lying felled by his own club.
• The God of Destruction, Malroth, much like many other elements in Dragon Quest II was really only formidable in the In Name Only implications. When Hargon finally achieves his goal, everything once only implied about Malroth is taken to its logical conclusion and played chillingly straight. The Dragonlord was of a similar potency, sure, but the setting of Alefgard came pre-equipped with the tailor-made means to vanquish him. Here? No such thing, and defeating this monstrosity seems genuinely hopeless as he, bit-by-bit, begins to destroy the world.
• Some of the monsters can count as this, with the Spirits and Mean Spirits being the best example. They tend to suddenly show up in the middle of the night or in a cave, and even come with a ghastly moan when they appear. As a result, they can be quite creepy.