Adventure Island/YMMV

• Crowning Music of Awesome: Super Adventure Island was soundtracked by Yuzo Koshiro. Enough said.
• Demonic Spiders: The literal spiders (aka Zigmos) can make some of the later levels Unwinnable if you lose your weapon. There's also those pesky frogs/Kellos. The literal Goddamned Bats can be particularly demonic when platform jumping. And the jumping swordfish come at you almost-nonstop in the later ocean levels.
• Goddamned Rocks. Bounce, bounce, bounce, die, throw your controller.
  • And there are also bassers which are bats which often qualify too.
• Guide Dang It: The success of button-mashing minigames in Adventure Island IV depends on how much food you have in inventory before entering minigame.
• Serial Numbers Filed Off: Made by the creator of Wonder Boy, and the first games are nearly identical.
• That One Level: Although the whole world 8 in the first game is very hard, the world 8-3 is especially noteworthy due to a segment which requires pixel-perfect jumps and firing.