Nightmare Fuel / Sonic 3 & Knuckles

• To start, Angel Island Zone has a moment early in that demonstrates both the technical upgrades the game has compared to prior titles - and the escalation of the otherwise-goofy schemes of Dr. Eggman from prior games into outright torching an entire forest with Sonic and co. in it. If that weren't enough, he even attempts to bomb the everliving hell out of our heroes, and then flies in past the background to a waterfall ambush to try to kill them personally in easily some of the most aggression the man showed in the classic titles.
• A very large portion of Hydrocity Zone is underwater, with all the series-traditional scares that go with it. Then Act 2 comes and it starts with an Advancing Wall of Doom with very loud rumbling noises.
• The Big Arms, when fought in standalone Sonic the Hedgehog 3, its grab attack is capable of knocking the rings out of Super Sonic. It's a shock to those used to the idea that Super Sonic is invincible to anything that isn't getting squished, a Bottomless Pit, or the time limit. To the extent that this ability is excised in the locked-on version.
  • The Big Arms in Sonic 3 can do this by just appearing thanks to the sudden Mood Whiplash. In one moment, you defeated Eggman's new mecha, and think that you've won. Then the sky goes dark, the slow and ominous opening gongs of the final boss music start playing, with the Big Arms falling in the background fast enough to only catch a glimpse of it. And then the fight starts, and the music suddenly takes a faster more frantic tone as Big Arms continuous sweeps in and tries to grab you.
• Everything about Sandopolis Zone Act 2 is creepy. Set inside a huge pyramid with a scarier/more depressing version of Act 1's theme playing in the background. About a quarter of the way through, you'll land on a capsule that dispenses a crowd of Hyudoros, ghostly enemies who start out small and simply hover near the top of the screen, but become larger and more menacing as the lights dim before finally turning hostile when the lights go completely out (pictured above). In addition, the solid thud sound those sliding doors make when they close can create a feeling of entrapment (especially with the lights off). On top of all that, the music itself is easily the darkest of any track in the entire game. It's especially bad when you start that act as Knuckles, since his story takes place after Sonic's, the lights are already off and the Hyudoros are at full strength, and they will ambush you first thing when the act starts with no rings to protect you. Better be quick about turning that first light on when starting that part of the game as Knuckles. Not helping matters is that this is one of the longest Acts in the entire game, if not all of the 16-bit Sonic games.
• The transition to the Lava Reef Zone Act 2 boss is so sudden that it effectively acts as a Jump Scare if you aren't aware of what happens next. One moment Knuckles is up to no good as usual, punching a boulder on you, the next moment the entirety of Lava Reef Zone is engulfed in flames as Eggman begins lobbing rockets at you. A bit of horror kicks in when you realize the Death Egg's eyes shined and suddenly the entire place is falling apart and the lava going active. With it just about fully repaired and close to activation, Eggman just activated his super death weapon and practically tore the whole area up as a result, implying it's powerful enough to decimate entire regions in a single blast. Sonic's lucky he wasn't at the focal point of the blast!
• The scene where Knuckles gets electrocuted when he tries to retrieve the Master Emerald can be scary to a few. Not to mention the device is plugged into his ears which can make for a very painful experience.
• There's something... weird about Giant Eggman Robo◊'s eyes. While the left looks like HAL, the right looks like a real eye with two outgrowing red ones on its right side.
• In the Doomsday Zone, if Super or Hyper Sonic's ring count drops to 10 or less, the already-frantic music will accelerate. If he runs out of rings, he falls out of orbit, and we can very much assume that he fell hundreds of kilometers and died of reentry burnup or the world's biggest freefall.
• If you lock-on the Sonic & Knuckles cartridge with anything other than Sonic 2 or 3, or if you do have either of those plugged in but the S&K cart can't read it correctly, instead of the usual startup routine you'll get a screen with "NO WAY! NO WAY! NO WAY! NO WAY?" scrolling at the top. While the screen isn't inherently creepy, it can still cause a bit of a Jump Scare if you didn't expect it.
  • Sometimes the S&K cartridge will fail to read the attached cartridge during gameplay (especially if the connection is faulty), which can be a much worse jump scare. Or if playing Sonic 2&K, a horrific frustration, since that game can't save; one minute you're struggling through Metropolis Zone, the next all your progress suddenly gets erased and all your emeralds and continues just went down the toilet!

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