These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Sue as well for taunting a gigantic frenzied Mimiga and then promptly getting pummeled into submission. But much less so.
Ass Pull: The relationship between the third to last boss and the last boss: killing the Load-Bearing Boss causes the island to fall, but killing the next boss causes the island to stop falling. Sloppily handwaved with something vague about "negative energy".
And those two brief sentences are all the information the game gives you on this matter, in stark contrast to the nicely fleshed-out backstory of the Load-Bearing Boss and the True Final Boss themselves.
Think about it this way. The island would float with or without the core. The core's true purpose is to act as an opposing force to Ballos as he is trying to pull the island down so he can die. When you break the core, Ballos is no longer restrained by it, and then when you kill him the island stops falling.
Best Boss Ever: The last five bosses are the pinnacle of the game. And the boss preceding them is a symbolic one.
Bizarro Level: The outer wall is by far the weirdest place in the game. The gravity is odd, treating the left side of the screen as 'down' for everything except you (though this could be justified if the wind is strong enough — this is the outside of a Floating Continent, after all). The enemies don't seem bizarre at first, but then you encounter the giant cat ghosts that shoot yarn balls at you. And living at the bottom is a group of people that are five inches high.
Breather Level: Plantation is rather easy compared to Outer Wall and what's to come - and what came before. Most of the enemies in this area are rather weak or easily avoidable, save points are plentiful and there are no bosses.
Complete Monster: The Doctor was initially with the research expedition to The Island, but his true purpose was to seek the Demon Crown and wield its power himself. He also kidnaps and performs Psycho Serum experiments on the local tribe of Mimigas in the hopes of transforming them into mindless monsters for his army and is working on a project to do the same thing to humans. He's killed several Mimigas and many baby dragons. The dragons left alive he turned into his undead servants.
And the actual bats in the game, which can swarm around you if you don't kill them while sleeping, and are particularly obnoxious when summon spammed by bosses.
Good Bad Bugs: Playing in Holiday Mode in the Wii version somehow turns Curly's sprite into Quote's. Not only is the now-male "Curly" referred to as "she" and "her", you still meet Quote in the Sand Zone. For the rest of the game two copies of the main character are running around the island.◊ And Curly's panties are still referred to as "Your Panties". Yeah.
Cave Story 3D has a huge glitch where the game saves flags between save files when you quit the game with the inventory open. This can be used to return from the Point of No Return, get huge amounts of HP, and numerous other wacky things.
Most Annoying Sound: The sound of experience points bouncing on the ground is barely noticeable in the original PC version, but drowns out everything else on the WiiWare port. This has been fixed with the recently released update.
Paranoia Fuel: One of earliest doors you'll have to enter is literally a monster. However, this monster never appears ever again after this initial trap.
"Curly's life functions have ceased." Five little words to let you know that you dun goofed.
Polished Port: The number of ports of the game are comparable to the number of ports of Lunar: The Silver Star, and each capitalizes on the last. The WiiWare port has redone sprites, the ability to play as Curly, and the European version gets an additional soundtracknote Later the NA version would have its debatable soundtrack replaced with the European soundtrack. Cave Story + has all this and the Wind Fortress, somehow harder than the Sacred Grounds. 3D has polygonal models, and Cave Story +'s eShop release boasts everything + does but the graphics, and to compensate it's in stunning 3D.
Shout-Out: Lots to Metroid. Aside from the similar "found a heart container" jingle, the first weapon you get is a laser gun whose range, damage, and shot types can be upgraded, followed by missiles. The Jellies may also be a Metroid reference
Monster X is a mine car that drives from one side of the room to the other, forcing you to climb on it to avoid being crushed, and can only be damaged when it stops to unleash a torrent of bullets or homing missiles.
The Core has five mini-cores that together create an impressive volume of fire, and severely hampers the player's mobility by frequently flooding the room. It Turns Red by adding a current to the water and starting to use an attack which takes off 20 HP (of a maximum attainable 41 at that point).
To drive the point home? Most bosses are doable without getting hit. When fighting Monster X and the Core, it is barely possible to not get hit. In the Wii/Mac/Steam version's Hard Mode, you MUST beat them without getting hit, because their weakest attacks do 3 points of damage, which is pretty much all the HP you're allowed to have in Hard Mode. Oh, and no missiles, either!
That One Level: The Sand Zone. The Egg Corridor prepared you, Grasstown/Bushlands is where the game really starts, the Sand Zone is where the Nintendo Hard and Guide Dang It nature of the game starts shining, featuring the first opportunity to miss out on one of the two Infinity Plus One Guns, enemies that gang up on you and can cause notable damage together, and a Fetch Quest that forces you to go through the area where the most enemies gang up on you at least five times and forces you to go through that area and the area after it twice. Not to mention Omega and Frenzied/Rabid Toroko, the first two Wake Up Call Bosses...
They Changed It, Now It Sucks: Balrog's quirky Catch Phrase ("Huzzah!") became an "Oh Yeaahhh!" for the WiiWare release. Fans were not pleased. Also, some of the music sounded worse, although in this case the consensus was nearly unanimous, with the real debate being how big a problem it was. Nicalis heard the complaints, and eventually released an update that fixed the sound, music, and a few grammar/spelling quirks.
What Do You Mean, It's Not for Kids?: The game is known for his accessible and engaging gameplay and cutesy visuals. It also features slavery and war themes, four nightmarish final bosses (The Doctor, who loses control and mutates, then him possessing the Core, Sue, and Misery, then the Heavy Press which attacks out of nowhere and is a Kaizo Trap if you don't realize what it is quickly enough, then finally Ballos, who has a horrific backstory and red, tortured faces in his head), and most of the cast dying before your eyes at regular intervals.