Nightmare Fuel / Shantae

  • Just to the east of Oasis Town is... well, in-game it's described as a "swamp", but the area looks more like something inspired by some nightmare one of the developers had as a kid. It's practically a small-scale Eldritch Location, with its amorphous black-purple blob creatures and pod-covered trees/columns/somethings topped off with what appear to be giant (five times Shantae's size giant) bugs of some sort. Considering the entire rest of the game up to that point had been fairly standard field/forest/desert environments, this one especially sticks out. The same lighthearted background music continues to play throughout the area, but that arguably just makes things worse.
    • We visit another "swamp" in Pirate's Curse, and not only is it still home to Dead Big Creepy-Crawlies and animated piles of carnivorous sludge, but it also houses a pocket of purgatory, not to mention a gate to Hell!
  • The Cackle Mound's miniboss is a collection of floating, screaming heads that appear when you fall through a trap door after defeating an enemy.
  • The first game has a day/night cycle. At night, enemies are a lot more dangerous and have dark palette swaps to reflect this, and the music changes to a frantic tune.
  • At the end of the first game, Risky threatens to slice Shantae to ribbons and dance on her runny innards.
  • At the end of Risky's Revenge, Risky uses the Magical Lamp to steal Shantae's genie half and make it fight Shantae. Even when the genie half is destroyed by fight's end, Risky escapes unharmed and leaves Shantae as a nearly powerless human.
  • Hexer in Pirate's Curse looks like a sketch for Hypno Baron who was rejected for looking too menacing. He's a ghoulish skeletal wraith with no limbs and a cyclops bug head, and speaks with a low hissing rasp of his "Master" being "displeased".
  • In Pirate's Curse you find out that the skull-bra and bone-like thong on Risky Boots's body is literally the skull of the Pirate Master. She took the skull of her former captain, and has been WEARING IT.
  • The Pirate Master's final form in Pirate's Curse is a huge, building-sized Eldritch Abomination.
    • Pirate Master IN GENERAL is terrifying. The Dreaded? Check. Waged war on the Genies? Check. Permanently killed a number of them? Check. It's debatable whether Shantae's nature as a half-genie would allow her to put him down for good.
  • After Pirates Curse suggested that Risky may not be all bad, Half Genie Hero completely dashes those hopes by giving her her darkest and most destructive Evil Plan yet. Rather than simply wanting to take over the world or rob everyone of their valuables, Risky wants to turn the Genie Realm into a Death World full of evil and decay that will then seep into the real world, either purely For the Evulz or so she could control the genies with her machine, as she states she wants the genie's powers.
  • Techno Baron's plan is pretty horrifying. He's been kidnapping mermaids and sticking them in tiny containers in order to sell them as monster chow. Then when there's not enough mermaids to meet demand, he starts kidnapping young maidens and sticking fish on them to make them into fake mermaids with the intention of selling them as well. While it's played somewhat comedic, it's still shocking, especially to see the factory in action.
  • Risky Boots is terrifying in her own right - she's not the main antagonist for nothing. In addition to hijacking the army and equipment of the Pirate Master, she's quite good at disguising herself, and she's a fearsome fighter whenever the player has to face off against her. Not only that, but she's a hell of a chessmaster, and actually wins in Risky's Revenge, sapping Shantae of her powers for an entire game. And when that backfires on her in Pirate's Curse, she still manipulates the situation to her advantage! On top of all of this, she's able to immediately figure out artifacts that nobody understands and then integrate them into weapons. Consistently. A scary lady, indeed!
http://tvtropes.org/pmwiki/pmwiki.php/NightmareFuel/Shantae