* SugarWiki/AwesomeMusic: [[AwesomeMusic/SonicTheHedgehog The soundtracks of both versions]]. It helps that the Genesis versions of the Green Grove and Panic Puppet tracks each got re-orchestrated for ''VideoGame/SonicAdventure''.
* BestLevelEver: The Special Stages from the UsefulNotes/SegaSaturn version are a fan favorite, being a vastly improved version of the Special Stages from ''[[VideoGame/SonicTheHedgehog2 Sonic 2]]''. These stages are rendered in true 3D and have more elaborate features like springs, gaps, and upper/lower paths. On top of that, they are less headache-inducing than the ''Sonic 2'' Special Stages. Some elements were retained in the ''VideoGame/SonicTheHedgehog4: Episode II'' Special Stages.
* BrokenBase:
** Since the Genesis and Saturn versions both have vastly different soundtracks, this game tends to suffer the same arguments as ''[[VideoGame/SonicTheHedgehogCD Sonic CD]]'' over which of them is the better one.
** Upon Jon Burton's unveiling of his official ''Director's Cut'' GameMod, fans immediately swarmed his forums and [=YouTube=] videos, completely divisive over many of the alterations made (or ''not'' made). The altering of the Flicky mechanics and the obligations for unlocking Super Sonic in particular left fans split down the middle.
* CommonKnowledge: The 2D illustrations made for the Japanese version of the game (and ''VideoGame/SonicJam'') were (and still are) commonly thought to have been done by Yuji Uekawa, due to the designs sharing similarities with his modern 2D illustrations. However, it was revealed in 2020 that it is actually the work of former Sega artist Satoshi Okano, who played a role in illustrating Sonic’s modern design in ''VideoGame/SonicAdventure'' alongside Uekawa.
* GameBreaker: The Red Shield on Volcano Valley turns the stage into a BreatherLevel since you no longer have to worry about anything that attacks with fire (which is a majority of obstacles in the stage) or platforming across lava since you can walk straight through it. Just don't lose it, or else it becomes ThatOneLevel as seen below.
* SugarWiki/GeniusProgramming:
** Director Jon Burton revealed that the Sega Saturn port of the game uses the exact same code as the Genesis version, just with a well programmed C language compiler that perfectly emulates the Sega Genesis' 68000 assembly language. All of the other new graphical effects could simply be laid on top then, as they don't interact with or affect gameplay.
** As Burton would go on to share in his behind-the-scenes videos, the sheer level of SceneryPorn in the Genesis game up to and including ''a CGI FMV intro'' were all only possible through judicious application of programming magic, graphical shortcuts, colour palette trickery, and compression trickery. As further seen with the enhanced Saturn port and the graphical might of ''[[VideoGame/SonicR Sonic R]]'', milking Sega consoles for all their potential was Burton's expertise.
** The Genesis version has a remarkable workaround for crashes: instead of simply halting the game when something would cause the game to crash (either the cartridge being jostled or the rare programming error), the game would "congratulate" the player for finding the secret level select menu.
* GoddamnedBats: The snowman Badniks in Diamond Dust Zone, which due to the isometric nature of the game are far more annoying and difficult to avoid and to kill than any of the Badniks in [[VideoGame/SonicTheHedgehog2 Metropolis Zone]]. And in this game, you ''have'' to kill them in order to complete the level.
* GoodBadBugs: In addition to the CheatCode activated level select, there's a second way to trigger it. As part of a kind of safety feature, the error handler for the game makes the game jump to a screen saying, "CONGRATULATIONS. YOU HAVE FOUND THE SECRET LEVEL SELECT SCREEN!", proceeding onto the level select. With the Genesis being as fragile as it is, the easiest way to do this is to simply ''smack the console'', especially during the pre-rendered 3D animation at the start of the game.[[note]]Jon Burton [[https://www.youtube.com/watch?v=i9bkKw32dGw revealed]] that this error handler was a clever (and successful) way to pass Sega's quality assurance more easily.[[/note]]
* HilariousInHindsight:
** Sonic's [[http://vgboxart.com/view/76380/sonic-3d-flickies-island-directors-cut-eu-cover/ odd-looking frontways model]] on the European cover of the game is eerily similar-looking to [[VideoGame/SonicHeroes Neo Metal Sonic]], due to the symmetry and the arrangement of Sonic's quills.
** The game features a minor shield power up that is ''very'' similar in function to the Homing Attack, a basic series move that wasn't introduced until ''VideoGame/SonicAdventure''.
* JustHereForGodzilla: Many who brought the Saturn version of the game got it only for the 3D parts, the special stages in particular.
* MemeticMutation:
** An [[https://youtu.be/4qAnfh8X8wU?t=42s unfortunate camera angle of Sonic's face]] in a pre-release of this game gave rise to a RunningGag on the Sonic Retro forums known as "[[FanNickname Down Syndrome Sonic]]" or "[[FanNickname Lazy-Eyed Sonic]]".[[note]]Jon Burton, the game's director, claims it was a result of using Sonic's model with its default expression, but the way it was angled unintentionally gave it the appearance of being cross-eyed. They doctored the models eyes to look better for the final version.[[/note]] Some forum regulars even include DSS in their ROM hacks.
** '''SEGA!'''[[note]]The Sega logo has someone screaming the company's name in a way that sounds like he's about to be murdered. This is meant to be akin to the western ''Sonic'' [[http://youtu.be/0T4O5zgJzdE?t=23 commercials of the time]] which would often have a similar chant near the end of commercials. Amusingly, some of the prototypes do feature the classic "Se-gaaaaaa!" chant.[[/note]]
* NightmareFuel: [[https://www.youtube.com/watch?v=8pYMWE88Jro The Saturn boss theme]]; instead of rock-and-roll like we're used to in the series, it's mainly focusing on tension with low-key pianos, Robotnik's [[EvilSoundsDeep deeply sinister]] EvilLaugh, and {{Ominous Pipe Organ}}s. It's similar to the [[VideoGame/SonicTheHedgehogCD US Sonic CD boss theme]] in that regard.
* OlderThanTheyThink: This is the first game to give Sonic his now iconic homing attack through a shield, before ''VideoGame/SonicAdventure'' and onwards made it a part of his default moveset.
* PolishedPort: The Saturn version substantially beefed up the graphics and palette with a variety of environmental effects, completely redesigned the Special Stages courtesy of in-house Sega of Japan developers, added analog control pad support, and provided a different CD-quality soundtrack composed by Richard Jacques. The major caveat, however, is that the load times are absolutely atrocious.
* ScrappyMechanic:
** Collecting Flickies, mainly for slowing the pace of the game, as well as drawing importance to what is normally an afterthought in other ''Sonic'' games. Fortunately, the Sonic 3D No Flickies ROM hack downplays this, and makes it far easier to get through the levels (flicky requirement is eliminated here).
** The Power Sneakers are basically worthless in this game; Sonic becomes even harder to control than ever, and it makes it very easy for him to accidentally plow into a nearby enemy or obstacle.
** The Saturn port, for all of its merits, introduces another unwelcome change from the Genesis version: as the Tails and Knuckles set of Special Stages were merged, you can only collect one Chaos Emerald per act as opposed to two, going to the Special Stage a second time in an act will always give you a 1-up, which [[FakeLongevity considerably drags out the pacing of the game]], which is already bloated by the [[LoadsAndLoadsOfLoading very tedious loading times]].
** Jon Burton's ''Director's Cut'' makes the Chaos Emerald situation even worse; you can only earn one ''per zone''. Which means you can't even unlock the newly added [[SuperMode Super Sonic]] until the very last non-boss level (and you can't even use him there due outside of replays), although the extra medal challenge prevents it being redundant altogether (assuming you didn't get all medals during your first playthrough).
** Also in the ''Director's Cut'' version, one of the requirements for OneHundredPercentCompletion is collecting 5 million points. Normally, [[ThePointsMeanNothing there's no real reason to pursue points in the game]], so most players won't, and by the time you complete the rest of the game (That is collecting all Sonic tokens in each of the levels, beating the Time Trials, and collecting all 7 emeralds), you'll be left with somewhere around one to two million. The game itself [[GuideDangIt never explains that points are important to game completion]], so after seemingly completing the game, only getting 90%, and looking up how to get [[LastLousyPoint that other 10%]], players will have to be ready for a grindfest...
** You are also allowed a limit of only 9 lives on the counter-- any others do not count, even if the 1-Up music plays when you get them, whether by hitting the 1-Up monitor, or getting 100 or 200 rings. Not only this, but even if you get several 1-Ups after 9, once you lose a life, your counter goes down to 8 as if you never got those 1-Ups.
* SoBadItsGood: The unused track, which was originally thought to be meant for Spring Stadium. It was nonetheless reprised in ''VideoGame/SonicTheHedgehog4: Episode I'' as the initial boss theme.
* SoOkayItsAverage: The general consensus on the game is that it's not ''terrible'', but the slow gameplay, the flickies mechanic, the Genesis special stages and the [[LoadsAndLoadsOfLoading long loading times on the Saturn version]] drag it down quite a bit.
* SuspiciouslySimilarSong: The Special Stage theme of the Genesis version sounds similar to the "Player Select" theme from ''VideoGame/SuperMarioBros2''. There's one ''Super Mario''/''Sonic'' connection not many expected. More intentionally however, it's a remix of ''Super Fantasy Zone's'' [[https://www.youtube.com/watch?v=EDkfol1PNBE Picnic level theme]].
* TearJerker: [[https://youtu.be/ezLGTcdZU8Q?si=6CClJtAnLvXWJc1N The credits theme]] has a bittersweet feeling to it, as this was the last Sonic game released for the Genesis/Mega Drive thus marking the EndOfAnEra
* ThatOneAttack: The homing flamethrower attack - as seen in the Volcano Valley and Puppet Panic {{Boss Battle}}s - is tricky to avoid due to the restricted spaces they're encountered in, making the already difficult bosses even more harrowing to fight. It also appears in the TrueFinalBoss battle, but the large arena makes it trivial by comparison.
* ThatOneBoss:
** Most of the later game bosses can be described as this, but Volcano Valley's is the worst. Having to cross thin pipes in an isometric perspective with a rather slippery control over your character with lava and a dragon following you makes this boss a life-stealer. This can be dealt with by attacking him quickly, but usually you'll end up getting hit and/or dying.
** The Saturn version averts this for Volcano Valley, where, with the right jumping, it's easy to connect successive hits on Robotnik and beat him in about 20 seconds. The honor for this one is Panic Puppet, whose attack patterns and specific hit areas make it harder than the true final boss.
* ThatOneLevel:
** Rusty Ruin isn't hard as a whole, but it becomes much more frustrating if you're trying to get to Tails or Knuckles. The big issue is that there are stone pillars obstructing your paths in both acts, and you have to use the Spinner devices nearby to destroy them -- and the controls for Sonic spinning around, which makes him a lot faster than usual, are very slippery and liable to get you knocked into an obstacle by accident, robbing you of the rings you need to access the Special Stages. Act 2 also has a very tricky platform on an angle you have to traverse, and due to the game's isometric controls, it is very easy to miss the jump and fall down to the area below it, forcing you to backtrack all the way up and try it over again.
%%** Diamond Dust Zone, the game's SlippySlideyIceWorld.
** Volcano Valley is a very frustrating LethalLavaLand with a ton of treacherous jumps over lava. Chances are that you'll end up getting hit and losing your Flickies more often than any other level in the game. However, if you can snag a Red Shield and hang onto it, the level becomes a piece of cake.
** Gene Gadget Zone Act 2 is a pain because of one section where you have to climb up a large incline by jumping between moving platforms and dodging enemies. This section is designed to loop around until you can manage to get all the Flickies, and it'll most likely take more than a few tries.
* SugarWiki/VisualEffectsOfAwesome: Particularly hardware-pushing for the Genesis:
** A ''full FMV'' for the opening cutscene. According to Burton, not even the people from Sega knew it was possible. [[https://www.youtube.com/watch?v=IehwV2K60r8 This video]] documents the painstaking efforts taken to make it happen, and it's [[SugarWiki/GeniusProgramming nothing short of ingenious]].
** ''Incredibly'' fluid animations for everything onscreen.
** The stages are very colorful and highly detailed. Its DigitizedSprites are on par with greats such as ''VideoGame/{{Vectorman}}'' and ''VideoGame/SuperMarioRPG''.
** Very fluid particle effects.
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