History YMMV / UndertaleYellow

** [[spoiler: Was Chujin's experimental failures because of his incompetence, or because he was the first to break new ground and thus had no way of knowing what was successful from the get-go? There were cases of real life inventors who spent their lives experimenting with unsuccessful prototypes (or even just conceptual designs) that were retroactively recognised as revolutionary precisely because they were the first to do so.]]

* FandomSpecificPlot: Combined with FanficFuel; considering the [[spoiler:bittersweet nature of ''Yellow'''s true pacifist route and Clover's sacrifice]], and the ambiguous fate of the human souls with their coffins being open in ''Undertale'''s own pacifist route, writers (and a few artists) have taken up writing stories and drawing comics (mostly the former) of [[spoiler:Clover, post ''Undertale'''s true pacifist ending, finding themselves revived right after Asriel's barrier destruction. Expect these stories to contain, in some way or another, Clover pushing and crawling their way out of their own coffin, meeting the ''Undertale'' cast, and eventually reuniting with ''Yellow'''s cast]].

** Ningen[[labelnote:Explanation]]Whenever Kanako and Clover are shipped together, [[spoiler:Chujin]] is often depicted as a [[DatingWhatDaddyHates an overprotective father who disapproves of their relationship]] and uses "Ningen" (the japanese word for "human") as a derogatory term towards Clover.[[/labelnote]]

** Ningen[[labelnote:Explanation]]Whenever Kanako and Clover are shipped together, [[spoiler:Chujin]] is often depicted as a [[DatingWhatDaddyHates an overprotective father who disapproves of their relationship]] who uses "Ningen" (the japanese word for "human") as a derogatory term towards Clover.[[/labelnote]]

** "Guys hear me out" / The 12/03/2024 incident[[labelnote:Explanation]] One Reddit user on the Undertale Yellow subreddit, made an post claiming to "[[https://www.reddit.com/r/UndertaleYellow/comments/1bdyugl/the_12032024_incident/ Hear Him Out]]" about an childhood picture between Ceroba and Starlo, where he explains that what he saw was not Ceroba sticking her tougue out, but saw it as her Buck Teeth. This sparked many similar posts, with "Hear me out" titles, which grew to the point of annoyance in the subreddit. "Someone calls for help, you hear them out." truly.[[/labelnote]]

** "See you in 5 years!"[[labelnote:Explanation]]Since ''Undertale Yellow'''s development took 5 years, whenever someone decides to [[FollowTheLeader make a prequel to Undertale based on another fallen human]], people like to joke that any such prequel will also take 5 years.[[/labelnote]]

* ShipsThatPassInTheNight: Although the two have barely interacted (outside of seeing each other in [[spoiler:the True Pacifist ending]]), people were quick to pair Dalv and Starlo together, [[OppositesAttract likely due to their opposite personalities]].

* GoddamnBats: On a pacifist playthrough, Sir Slither can be a bit hard to figure out how to spare at first. [[spoiler:Unlike most monsters, you have to be a jerk to him by declining his offer to join you twice in a row. If you do anything else after declining once, your progress resets.]]

** For some reason, people have made [[spoiler:Chujin]] obsessed with ''WesternAnimation/Ben10''.

** There is a recurring headcanon of Martlet being an amputee and having prosthetic legs, mainly due to her namesake being a mythical bird that lacks any sort of feet.

** "See that heart? No shit!"[[labelnote:Explanation]]YouTuber [[https://www.youtube.com/@CiblesGD/ CiblesGD]] had an AI [[https://www.youtube.com/watch?v=avG2WAaF9oA rewrite the entire script of the game]], which led to Flowey saying this over and over. The line quickly became a meme, being spammed in livestream chats whenever Flowey is onscreen.[[/labelnote]]

** "The Myth Of Consensual Copyright" / Let's Unpack the Music of Undertale Yellow [[labelnote:Explanation]]In December of 2023, ''Undertale Yellow'''s soundtrack was hit heavily with copyright issues due to Materia Publishing (the distribution service that put Toby's works for ''Undertale'' and ''Deltarune'' under copyright protection on platforms like Youtube). This was in spite of the fact that Toby has always promoted the usage of his songs in fanworks and video essays, as well as the fact that Toby gave permission to the creators of ''Undertale Yellow'' to use certain familiar Leitmotifs in their game. The fact that it's '''only''' Materia Publishing making such a big deal about the copyright claims has not been lost on the fans, as such memes about "Materia not giving Consent" and copypastas in reference to Materia's opening Tweet about the ''Undertale Yellow'' situation have been made of the subject matter because of it.[[/labelnote]]

** "See that heart? No shit!"[[labelnote:Explanation]]YouTuber [[https://www.youtube.com/@CiblesGD/ CiblesGD]] had an AI [[https://www.youtube.com/watch?v=avG2WAaF9oA rewrite the entire script of the game]], which led to Flowey saying this over and over. The line quickly became a meme, being spammed in livestream chats whenever Flowey is onscreen[[/labelnote]]

** [[spoiler:Ceroba's fight in the Pacifist route is a very frantic and fast-paced encounter. Her visual design, variety of attacks and mechanics, and the absolute banger that is "A Mother's Law", makes for an absolutely epic, yet tragic final boss fight.]]

* BestBossEver: [[spoiler:Flowey's fight in the neutral run is often stated to be one of the game's strongest points, with Flowey's trippy attacks in the first phase ringing true to his ''Undertale'' characterization, and his second phase evoking the same feeling Omega Flowey did, with the various switching of vastly different art styles for each phase being a testament to the team's creativity. Add in the AwesomeMusic that is "BEST FRIENDS FOREVER" and "AFTERLIFE", and you've got one of the coolest bosses in any ''Undertale''-related media.]]

** Guardener doesn't look feminine in the slightest, aside from the platform on her head vaguely resembling a flowered wide-brimmed hat, so the mention of her gender during the battle has come as a surprise to many players.

* ViewerGenderConfusion: Some may have thought Martlet was a boy at first sight, because of her color scheme that is [[TrueBlueFemininity covered in blue]].

** Trial by Hummer[[labelnote:Explanatiom]]Originated from a [[https://www.youtube.com/watch?v=0O6II_YWRSo video]] that mixed [[spoiler:Ceroba's Genocide theme]] with the Hummer Driver cutaway gag from ''WesternAnimation/FamilyGuy''. This has led to jokes about Ceroba committing [[CarFu vehicular manslaughter]] against Clover.[[/labelnote]]

* BestBossEver: [[spoiler:Flowey's fight in the neutral run is often stated to be one of the game's strongest points, with Flowey's trippy attacks in the first phase ringing true to his ''Undertale'' characterization, and his second phase evoking the same feeling Omega Flowey did, with the various switching of vastly different art styles for each phase being a testament to the team's creativity. Add in the AwesomeMusic that is "BEST FRIENDS FOREVER" and "AFTERLIFE", and you've got one of the coolest bosses in any m'Undertale''-related media.]]

* GoodBadBugs: The Golden Cactus is an item that, upon use, hurts you for 5 HP, and then for three turns afterward, heals you for 15 HP per turn. It's a risky, but powerful healing item, and you only get one… [[spoiler:However, the counter that tracks the turns that it can heal for is ''not'' reset after death or at the end of battle, meaning that if you die immediately after the first bite, you start the battle again with all three turns of healing ready for you.]] Okay, that's useful, but not ''super'' broken, right? [[spoiler:Except that by dying, you get it back in your inventory again. And if you use it while the previous one is still in effect, it ''extends the timer.'' Meaning you can build up dozens and dozens of turns of passive healing, and ''still'' keep it in your inventory when you stop abusing the glitch and finally take on your opponent for real, to use it again when you come to the next one.]] The bosses of the Genocide route aren't exactly a cakewalk even with this glitch, but it does significantly lower the difficulty into a more manageable range.

** "The Myth Of Consensual Copyright" / Let's Unpack the Music of Undertale Yellow [[labelnote:Explanation]]In December of 2023, Undertale Yellow's Soundtrack was hit heavily with Copyright Issues due to Materia Publishing (The Distribution Service that put Toby's works for Undertale and Deltarune under Copyright Protection on platforms like Youtube). This was in spite of the fact that Toby has always promoted the usage of his songs in Fanworks and Video Essays, as well as the fact that Toby gave permission to the creators of Undertale Yellow to use certain familiar Leitmotifs in their game. The fact that it's '''only''' Materia Publishing making such a big deal about the Copyright Claims has not been lost on the fans, as such memes about "Materia not giving Consent" and Copypastas in reference to Materia's opening Tweet about the Undertale Yellow situation have been made of the subject matter because of it.[[/labelnote]]

** "hey clover, check out my new cut" / Bald Flowey[[note]][[Website/TwitterX Twitter]] user [[https://twitter.com/marsh_ber marsh_ber]] posted [[https://x.com/marsh_ber/status/1740441392244236509 a Discord screenshot]] of themself with a profile picture of a petal-less Flowey stating the aforementioned quote. The image quickly spread throughout the fandom due to the sheer hilarity of it, with many creating their own versions of the "Bald Flowey" sprite. Many artists have also taken to depicting the scenario in comic form, where Clover usually tries hard to hide their dismay when a Bald Flowey shows off his "cut" to them. Became AscendedMeme when an official artist [[https://twitter.com/AeroArtwork/status/1744098187734896969 posted sprites of Bald Flowey]].[[/note]]
** Trial by Hummer[[note]]Originated from a [[https://www.youtube.com/watch?v=0O6II_YWRSo video]] that mixed [[spoiler:Ceroba's Genocide theme]] with the Hummer Driver cutaway gag from Family Guy. This has led to jokes about Ceroba committing [[CarFu vehicular manslaughter]] against Clover.[[/note]]

* PopularWithFurries: Just like with the Original, Undertale Yellow has proved to be very popular with the furry fandom, with Martlet and Ceroba getting the most fanart. While arguably not as popular, characters such as Chujin, Moray, and even more obscure characters such as Dina or the Honeydew Shopkeeper have gotten a fair bit of attention, too.
* SelfFanservice: Sometimes you may come across fanart of Starlo with a stronger build. [[spoiler: Some also get rid of his NerdGlasses and simply give him opaque eyes.]]

** While [[spoiler:Ceroba]] is necessarily hard on the Pacifist route as [[spoiler:the final boss]], she’s far from a slouch on the Genocide route. [[spoiler:Her attacks involve a multitude of blue and orange waves traveling near the entire length of the movable area, as well as red attacks which ''decrease your maximum HP'' if you’re unlucky enough to be hit by one. She takes it up a notch in her second phase by making it so ''the walls themselves'' not only do damage, but decrease your maximum HP like the red attacks. It certainly doesn’t help that she’s one of the most resilient bosses in the game in terms of HP, making it so that anyone who would attempt a Genocide run is in for a VERY rude awakening.]]
** Some of the bosses in the Genocide route are often compared to Franchise/TouhouProject for a damn good reason, but in the final boss' case, it's an unfavorable one since [[spoiler:Zenith Martlet is seen by many as unfair if not borderline. Her attacks are ''incredibly'' hard to dodge even for experienced players to the point where dealing with the faster-paced ones boil down to [[LuckBasedMission "spam the fire and dash buttons and hope for the best."]] Autofire, top-tier healing items such as Gunpowder, and spamming the Endure option during the second phase of the fight when said items inevitably run out[[note]]which was only added in Version 1.1, by the way.[[/note]] are outright mandatory to stand a chance and you're still likely to get your ass kicked even then.]]

** Speaking of Starlo, the other four members of the Feisty Five - Ed, Ace, Moray, and Mooch - don't have it much better. Despite being a gang of characters with unique personalities and designs, all they get is a short fight that ends automatically after a few turns and a couple minutes of extra screentime on the Pacifist route. [[spoiler:They don't even show up on the Genocide route, despite the opportunity for a boss fight with the entire Feisty Five all at once. While this is [[JustifiedTrope justified]] due to them evacuating, it's still a disappointing waste, especially considering Starlo's role in the route]].
* TheyWastedAPerfectlyGoodPlot: [[spoiler:Kanako is shown to be one of many monsters who were sent to Alphys’ lab after Ceroba injected her with the Determination. At the end of Axis’ fight on a Pacifist run, given how Ceroba’s motivations revolve around her daughter and thinking she’s still alive, you would think that the True Lab would be where she’s rushing to with Starlo in pursuit. Barring that, at the end of her FinalBoss fight, the idea of investigating what happened to Kanako is brought up. Other routes seem to indicate that the story would go in that direction, with part of Flowey’s boss fight in Neutral has Clover hear him in what’s implied to be him waking up there for the first time, and Martlet going into the lab in a flashback during a Genocide run. Instead, Ceroba unexplainably runs off to New Home, Clover decides to sacrifice themselves with the others reluctantly agreeing way too easily (Ceroba especially), and Kanako isn’t touched upon again.]]

** [[spoiler:Chujin's Axis prototype ''murdered'' a human instead of capturing it thanks to a programming oversight, but instead of owning up to his mistake, he concealed the evidence, took the SOUL for himself, and tried to get Axis approved for mass production -- only to present so many failed attempts that even [[NiceGuy Asgore]] got fed up with him. When he was finally dismissed from the Steamworks for his engineering mishaps, he again hid the truth from his family and turned his attention to the stolen SOUL, using himself as a test subject for his Determination theories. It's implied his experiments fatally damaged his own SOUL and resulted in a drastically shortened lifespan, leaving his family to grieve [[AllForNothing without accomplishing any of his goals]].]]

* TheyWastedAPerfectlyGoodCharacter: Starlo, at least in a Genocide run, [[spoiler:might as well be the Mettaton NEO of the game when comparing it to the original. With Martlet being an absolutely brutal FinalBoss and Ceroba getting a second gruelling boss fight, one might assume Starlo would get the same treatment. Maybe he finally becomes the sheriff everyone believes he is, or drops the facade and fights Clover as himself? Instead, he challenges you to a shoot-out [[ZeroEffortBoss that can't be lost]] due to [[TooDumbToLive him using a Toy Gun against the person who's been killing everyone.]]]]