This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / Indiana Jones and the Fate of Atlantis
The comic's version of Kerner and Ubermann using the God Machine. They don't even survive the transformation, instead horrifically mutating and melting (a la Toht's death in Raiders) away at the same time (Kerner ends up as a pile of smoking goo on the ground, and Ubermann's EYES BURST OUT OF HIS MUTATED HEAD at the end of his transformation.
To be more precise In the comic, the God Machine doesnt work at all, it NEVER DID. Its not a matter of putting in the right amount of Orialchum beads, the God Machine is a failed experiment created through the mad hubris of a decaying civilization attempting to ascend to the same level as their alien "gods"
In the game, the inner circles of Atlantis start to become this as time goes by, especially if you haven't rescued Sophia yet. Up until now, the Lost City hasn't seemed too frightening: the hallways are immensely wide and brightly lit, the ruined architecture is a little too grand to be frightening, and the Nazis are always patrolling the area to provide a reassuring series of fist-fights; after the canals, the random encounters end, and you're allowed to wander freely through the dimly-lit claustrophobic hallways of the second circle, all alone except for the eerie carvings on the walls and the skeletons on the ground.
Another element that adds a layer to the creepiness factor: the skeletons themselves. Maybe it's just the graphics, but quite a few of them look as though they died screaming in agony. If you decide to examine the bones, you can hear the uneasiness in Indy's voice as he describes them.
Maybe they're animal bones.
No animal I know about has bones like these...
These bones are weirdly twisted.
Any human being with bones like this had to have been diseased.
Some of the skulls bear half-grown horns.
Maybe they weren't human at all, but... something else...
It becomes especially so when by the end of the game it becomes clear that what Kerner became is about the same as the skeletons on the ground. The skeletons are the failed experiments from the God machine.
The canals themselves are guarded by a giant octopus.
When Sophia first puts the bead in her pendant and Nur-Ab-Sal appears for a brief second. It's not exactly nightmare fuel, but genuinely creepy.
It's even worse when you put a bead in her pendant while she's possessed. Suddenly the pendant's face changes to give you a creepy Slasher Smile.
Sophia's possession by Nur-Ab-Sal. It's even hinted at through the game at certain points where she'll start speaking in a deep masculine voice briefly if you choose certain lines of dialogue.
Being lost in the Greater Colony and finding the remains of previous explorers. Including Sternhart.