Sonic 3 and Knuckles/YMMV


 * Anticlimax Boss: The final boss in the normal version of Sonic 3 is just a standard-issue Robotnik flying machine except with a spiky top. In fairness, this was never really supposed to be the final boss fight; it was just something hurriedly thrown together once it became obvious that the game would have to be split in two.
 * Breather Level: Hidden Palace Zone. Mushroom Hill is also this if you lock on both games, as it's the first level of Sonic and Knuckles. It's quite easy and is shorter than most of the levels in both games. Ice Cap is also notable because it's quite short, but has difficult bosses.
 * Crowning Music of Awesome: It's a Genesis Sonic game. So pretty much the entire soundtrack qualifies. What's really cool is that, rather than using the same music twice per Zone, each Act 2 features a remixed version of the Act 1 theme.
 * The Ice Cap Zone theme seems to be particularly popular, if its status on Overclocked Remix as one of the most-remixed tracks, ever, is any indication.
 * The soundtrack also got additional respect once word got out that Michael Jackson's sound crew partially composed it. Many parts of each song are either heavily sampled from or inspired by his Dangerous album and standalone tracks.
 * Demonic Spiders
 * Chainspikes, the blue enemies in Death Egg Zone with 4 spikes.
 * Orbinauts, black orbs with four spiked balls orbiting their body, from the Launch Base Zone. Unlike their ice counterparts in the previous level, Orbinauts are smart enough to keep the spiked balls instead of throwing them out and leaving themselves defenceless.
 * Scorps, the brown mechanical enemies in Sandopolis that attack by trying to sting you with their spiked tail. Their attack is almost impossible to dodge, and if you do somehow dodge it, you'll have to watch that it doesn't hit you when the tail comes back.
 * Game Breaker
 * If Super Sonic or Super Knuckles broke the game, then Hyper Sonic, Hyper Knuckles, and Super Tails took the pieces and ground them into a microscopic powder. This is most likely the reason that subsequent Sonic games tended to reserve the Super Modes solely for the final boss battle.
 * Sonic Adventure didn't have Super Sonic because they couldn't figure out how to pull it off (there's even a hidden message with Tikal explaining how to turn Super). Of course, there's been many games since then that they could have spent trying to figure out how to pull off Super Mode in ordinary gameplay.. They are bringing it back for Sonic 4, thank God.
 * The Hyper Modes are quite powerful, but the Bonus Stages make them true game breakers. In Sonic 2, Super Sonic was more balanced since every level had a finite number of rings and hence a hard time cap on how long you could stay super. But in Sonic 3 & Knuckles, the Anti-Gravity/Glowing Sphere bonus stage allows you to earn oodles of rings with relative ease when you know how to play it. You can also manipulate the system because the Bonus Stage you go to at a Starpost is determined not randomly, but by how many rings you're carrying. By playing only the Anti-Gravity bonus stage at each Starpost, it's possible to finish every act with 999 rings, which are worth 999 seconds of super transformation time. That's over 16 minutes, and the game's timer allows you only 10 minutes per act.
 * And then there's a potentially literal game breaker with the debug mode.
 * The insta-shield (which attacks enemies while protecting Sonic, and can be used anytime without a proper shield) and the lightning shield (which doubles Sonic's jumping height) make most bosses a cakewalk. For instance, when facing the Launch Base Act 2 boss (which is one of the final bosses in the standalone Sonic 3), instead of facing Robotnik properly, you can Lightning-jump up to his "nest" area prior to the boss battle, and defeat him literally before the battle even begins.
 * Having a second player play as Tails in Sonic & Tails mode can easily dispatch most enemies and bosses, since Tails can't lose rings when hit.
 * Goddamned Bats:
 * "Skorp", the scorpion in Sandopolis Zone. Touching the spiked ball on it's tail get the player character hurt, and it will also use the tail and try to attack Sonic at an aimed angle. And it's very accurate.
 * Same goes for the ghosts in Act 2 of the same zone, especially when it is dark-- they grow big and attack in numbers, and they can't be killed off permanently!
 * Well, not until you turn the light back on.
 * "Blastoid" can be a bit of a Goddamned Bats in Hydrocity Zone. Especially since he will inevitably hit you at least three times throughout the level. Most likely even more, considering his placement.
 * Good Bad Bugs:
 * The points from destroying successive robots or bricks went 100, 200, 500, 1000, and stays at 1000. But there is a mechanic left over from the original Sonic The Hedgehog game: upon destroying the 13th object, the score jumps to 10,000. There is only one area in the original game this can be done (you can destroy 16 blocks in a row if you do it right), but there's also one in Sonic The Hedgehog 3: in the Launch Pad zone, right near the beginning, there's an alarm that summons a flying robot. Doing a spindash in that alarm and staying there to keep setting off the alarm will summon robot after robot, which fly right into Sonic and are destroyed.
 * In Sonic 3 by itself, through some stage select hijinks, you can get the game to play music from the wrong stage.
 * Have you ever wanted to hear Sonic & Knuckles' mid-boss theme while fighting a mid-boss in standalone Sonic 3? Here's how. Also, this fight plays the wrong (major boss rather than mid-boss) music to begin with...
 * In Launch Base zone, there is a part of the level where Robotnik/Eggman in his eggmobile tries to fly off with a box. However, he only flies off if the player jumps up to a certain height. As such, if the player is playing as Sonic and Tails, he can use the 2P controller to control Tails and attack Robotnik. After 256 hits, Robotnik pops like a regular badnik and releases either a blue bird or a white chicken. See the video here. Now we know the real reason as to why he was called Eggman.
 * You Just Had to Say It.
 * When ducking, you'll scroll the screen downwards. With some precise movements, it's possible to go inside the floor, possibly skipping some sections of the level.
 * And there are plenty more documented by YouTuber ORKAL (though not all of them are so benevolent):
 * Basic Techniques
 * Angel Island
 * Hydrocity
 * Marble Garden
 * Carnival Night Part 1
 * Carnival Night Part 2
 * Ice Cap Part 1
 * Ice Cap Part 2
 * Launch Base Part 1
 * Launch Base Part 2
 * Launch Base Part 3
 * Mushroom Hill
 * Flying Battery
 * Sandopolis Part 1
 * Sandopolis Part 2
 * Lava Reef Part 1
 * Lava Reef Part 2
 * Sky Sanctuary
 * Death Egg
 * Glitch Potpourri
 * Magnum Opus: Many consider the combined game to be the absolute high point of the series and the Magnum Opus of Sonic Team, since everything from the graphics, level design, character abilities, and even some story have been acclaimed as very best in the series.
 * Memetic Mutation: Michael Jackson's involvement with the soundtrack of Sonic 3 has inspired many a Sonic/MJ music mashup, with some...interesting results.
 * Nightmare Fuel: Sandopolis Act 2's ghosts.
 * The moving wall in Hydro City Act 2, especially if you played the game as a kid.
 * Player Tic: So who else presses up rapidly on the control pad after beating Robotnik to make it look like the player character is laughing?
 * Scenery Porn: Beautiful pixel art, and impressive parallax scrolling on the backgrounds.
 * There are a lot of little cosmetic details to the graphics that were in no way necessary to making the game and are clearly an example of Doing It for The Art. Angel Island, Sandopolis Act 1, and the boss area in Lava Reef have a heat ripple effect. Hydrocity has little drops of water falling from the ceiling. Mushroom Hill has little bits of pollen and leaves that are scattered when you run past (and also obey the wind currents present in the level), both the big mushrooms and the little mushrooms in the foreground wiggle, and its second act has palette-swapped segments that may represent different seasons or climates. Also, in any level where there's water, the surface of the water in the background will always match up realistically with its surface in the foreground, which at the time was no mean feat.
 * Scrappy Mechanic: Despite the levels being between two and three times the size of what was seen in the previous Sonic games, the ten minute time limit remains. This can render it literally impossible to complete some of the longer levels on a single life if you make even the slightest mistake while navigating the level, particularly the second acts of the Carnival Night and Sandopolis Zones.
 * Stop Helping Me!: Tails, when he's tagging along with Sonic. If you get a friend (or yourself ) to control Tails with the player 2 controller, he can be extremely helpful. But if the AI controls Tails, then he'll get in your way, collapse platforms that you want to use, attack enemies and bosses half a second before you do (so they'll have Mercy Invincibility by the time you hit them), and all-around make a nuisance of himself.
 * That One Boss:
 * Marble Garden's boss can be annoying to defeat with Tails alone. While Knuckles faces a entirely different boss and Sonic can hop on Robotnik's head with no problem, Tails must carefully fly towards the lower part of his pod taking care to not hit either the drill in its front or the fire on its back, since his tails are the only part that can cause damage while flying.
 * Marble Garden's mini-boss can also be problematic with Knuckles. Not only does his shorter jump make it harder to reach, but the spikes platform also retracts and protrudes every second, meaning you have a shorter window to properly hit the boss while using a character that takes longer to do so.
 * Red Eye is That One Miniboss, having two phases and can be rather tricky when trying to fight without getting hit. Other minibosses in this game tend to be easy.
 * Both the miniboss and main boss of Ice Cap Zone are considered this by some players, the former because it's hard to hit, and the latter because its freezing attacks are randomized.
 * That One Level:
 * Carnival Night Zone, Act 2. The level seems designed to waste your time, so that you'll invariably run out the timer while fighting Robotnik (unless you use Sonic's insta-shield against him). And it features the infamous Barrel of Doom...
 * Sandopolis. That level also really wastes your time, and the ghosts in Act 2 really get on your nerves after a while.
 * Ice Cap Zone is another "waste a lot of time" level. There's an awful lot of those types of levels and bosses in this game, which makes sense, since Robotnik's trying to prevent you from reaching the Death Egg before he relaunches it.
 * Many of the Super Emerald stages in S3&K are headaches, if only because their level design is really weird.
 * They Changed It, Now It Sucks: The PC port known as Sonic & Knuckles Collection bothers some players because all the music is remixed, and several music tracks are outright changed, including Ice Cap Zone. That said, several of the remixes and new tracks can be quite good in their own right. Look them up and judge for yourself!
 * Unfortunate Character Design: The miniboss of Carnival Night, as well as the boss of Flying Battery, are both rather freudian in design. The Flying Battery boss is especially blatant.
 * Unfortunate Implications: The commercial for Sonic & Knuckles featured elves pitching the game to Santa Claus, implying that the game would have been an unauthorized sequel. Fortunately, Santa had an It Will Never Catch On mindset, so the elves sold the idea to Sega instead.