Undertale/YMMV

• Alternate Character Interpretation: Hoo boy. Just about everyone invites this to some degree, though the biggest offender is easily the Fallen Child.
  • Just how evil are they to begin with. Were they evil in the first place? Were they simply a troubled child who loved their adopted family and tried to open the barrier out of feeling sympathy for the monsters' mistreatment at human hands? Or were they a nasty, manipulative sociopath who viewed the Dreemurrs and all of monsterkind as the perfect tools they could manipulate in order to wipe out their own kind?
  • The reason why the Fallen Child decides to kill EVERYONE during a Genocide run. Did the player's violence somehow corrupt them into becoming worse than they originally were, or did they come to hate monsters of their own accord? Also related: is the Fallen Child actually committing the murders, or was merely dormant until the player/Frisk began doing the deed?
  • And perhaps the biggest one: did they ever love the Dreemurrs? A lot of their behavior towards Asriel seems to indicate an abusive/codependent relationship with the Fallen Child as the abuser, though others argue that the Fallen Child did care for their surrogate brother and was simply bad at showing it.
  • Some fans recently have taken a third option with the Fallen Child, suggesting that they were always evil, but beforehand they was an (extremely ruthless) Anti-Villain until the "betrayal" by Asriel shattered their worldview and caused them to Jump Off the Slippery Slope.
  • A more minor example but when they say that the player has a "sick sense of morality" if we play the genocide route twice - is this because we played the genocide route twice, or because while there fine with killing for power, killing for fun is too much for them; or alternatively, were they COMPLIMENTING the player?
  • Dr. W.D. Gaster even more than the Fallen Child, as his actual existence is mere speculation.
  • Sans. Particularly when he claims he would have killed you if not for his promise to Toriel (though he pases it off as a joke) generates questiond to say the least....
• Angst Aversion: Not the game itself, which, when played as a Pacifist, is quite uplifting, but with the Genocide route. A lot of players, especially ones that got especially attached to the characters, actively avoid it (and any fanart and fanfic surrounding it) because they just find it too sad. This is of course the point.
• Anticlimax Boss:
  • Mettaton NEO. He looks strong, but the player takes him out in one hit.
  • During a True Pacifist run, the fight with Asgore will end before it even begins.
• Awesome Ego:
  • Papyrus thinks he is the most awesome person in the whole world. You still can't help but love him because he's always unflinchingly nice and helpful to everyone. He never looks down on people with smug superiority, but wants to help everyone else be almost as awesome as he is (equaling him is impossible)!
  • Mettaton. Just about everybody both in-universe and out thinks he's absolutely delightful.
• Base Breaker: Alphys and Asgore are easily the biggest examples, with Toriel not too far behind.
  • Asgore has people split into two camps: there are those who view him as irredeemable for being responsible for the deaths of six children and think that Toriel has every right to view him as a despicable monster no matter how horrible he feels about it. Others, however, absolutely love him for being a rather complex and tragic Anti-Villain who was dealt an absolutely shitty hand in life thanks to the death of his two children leading him to make a horrible mistake in the heat of the moment.
  • Alphys, however, is even more decisive for similar reasons as Asgore: she made a lot of awful mistakes that she regrets deeply, such as setting up a lot of dangerous obstacles she'd help the player overcome in order to boost her self-esteem, and creating the horrifying, tortured Amalgamates due to recklessly experimenting with determination. These have led to people loving and pitying her, while others look at her with scorn and view her as an irredeemably selfish bitch. Not helping matters is how overbearing her geeky, status-update spamming personality is: with some loving her for being a goofy nerd, while others loathe her for being obnoxious.
  • While generally well-liked thanks to making a good first-impression, her actions in the True Pacifist ending have really gotten people's opinions split on Toriel. While some think her cold, harsh treatment of Asgore is justified due to his actions, others think it's needlessly mean-spirited and cruel to kick a broken, grieving man while he's already down. Not helping matters is the relevation that she was his queen, and that she ditched the throne to leave Asgore by himself. Was she in the right to abandon him due to abandoning the principles he once stood for? Or is she a selfish, hypocritical bitch for calling him a spineless coward when she herself abandoned him and their people during their time of need though the latter is largely mitigated by several neutral run endings which show she very much would have led her people if not for the war?
• Broken Base: Whether or not shipping "Charasriel" (the Fallen Child and Asriel) is acceptable. Some say it's incest while others point out they are not blood siblings.
  • Whether DELTARUNE should be considered Undertale 2 or not. Those who say the latter claim that the games lore is too differant to fit continuity wise and should be considered an AU. Others point out the heavy implications that this IS the main timeline but some outside force messed with it.
  • Who was "right", Toriel or Asgore (see Ron the Death Eater below)?
• Common Knowledge: Some have criticized the game's route system for "Punishing you for defending yourself", and both fans and critics seem to be under the impression the Pacifist route is meant to be the game's goal your supposed to achieve. In truth, there are several neutral routes where the ending is bittersweet at worst, with the bad neutral endings only showing up for characters you kill needlessly.
• Complete Monster: While they're subjected to a lot of guesswork and theorizing in regards to how evil they truly are, this is definitely how the Fallen Child can come across when one looks at their actions and personality in the game proper. While they were definitely a troubled child in life, a Genocide run ends with them taking control from the player and committing not only patricide and fratricide, but omnicide as well. While the player was the one responsible for killing all the monsters leading up to this moment, the Fallen Child still makes the active choice to not only wipe out the game's world themselves whether the player likes it or not, but to sabotage the best ending by killing everyone, even their own adopted family afterwards should the player go for one again.
  • Of course, the players themselves can aim to be one should they wish. While the Fallen Child is the one pulling the strings for the last portion of the game, in a Genocide run, the player themselves made the choice to kill every monster in their way, no matter how friendly or innocent they were, and you can easily go out of your way to be as cruel as possible: you can stab Toriel in the back after convincing her to stand down, murder the Royal Guards in front of each other after getting them to confess to one another...
  • While first playing through the game, this is definitely how Flowey comes across: he's a spiteful, hateful, sadisitic little freak who tries to get the player to accept his and the Fallen Child's kill or be killed mindset, murders a defeated Asgore, and absorbs the fallen children's souls in order to gain godlike power, which follows with him attempting to kill all monsters and humans alike and sadistically toying with and torturing the player before his defeat. But as you play through the game more and explore the other endings, it turns out that there's a lot more to Flowey than what meets the eye, and the hidden depths and tragic elements reveal that while he seems to be actively aspiring to become one, he truly doesn't fit the bill.
• Counterpart Comparison: Steven Universe fans have made comparisons between Jasper and Undyne. Both are Blood Knight warriors for there species and both hate humans while still being seen as a hero by there respective species. Of course, Undyne could be considered a Foil to Jasper as Undyne is still an Anti-Villain while Jasper (while having a sympathetic past) is a sadistic egomaniac.
  • It's noted that much of what Flowey says wouldn't sound out of place coming from The Joker. His obsession with tormenting the player character and desire to goad them into killing can also be seen as a mirror of the Joker's obsession with tormenting Batman. Even one of Flowey's Nightmare Faces looks like the Joker's face.
  • Some fans of Gravity Falls have made comparisons between that show's main villain Bill Cipher and both the Fallen Child and Flowey. Flowey, like Bill, is a Large Ham sadist with a dark sense of humor. Particularly in his boss fight where he becomes an Eldritch Abomination and gives a corrupted version of the opening, just like Bill does. Meanwhile, the Fallen Child is a demonic figure who evokes Deal With The Devil.
• Evil Is Cool: Flowey is well remembered for his sadistic charm, and somehow making a FLOWER scary.
• Ensemble Darkhorse: The game is FULL of popular characters, but one in particular... the Fallen Child is one of the most popular characters on the game despite only actually appearing for a single scene. Mostly due to the mysteriousness of there personality leaving a lot to Fanfic Fuel, as well as there nightmare inducing one scene.
• Fanfic Fuel: Lots of it. Fans absolutely love to speculate what's the Fallen Child backstory or personality, what was Gaster like, what are many of these mysterious monsters' backstory, what were the other humans like, what's even the player character/Frisk actually like... and of course, anything and everything about Sans.
• Gateway Series: To Bullet Hell games.
• Genius Bonus: If you approach Mettaton's seemingly-joke train question, you'll eventually find out that 32.058 minutes is, in fact, the correct answer.
• Hatedom/Fan Dumb: During the moments of biggest popularity, the fandom was infamous for generating them, and of course, hatedoms and hate dumbs came around as well. Particularly, the fandom garnered infamy due to contentious aspect as the popularity of Sans (with many self-insert fics where the authors shipped themselves with him, along with many people disliking the amount of AUs based on him while believing there should be more of other characters, led to Sans being called "overrated"... ignoring the obvious fact they could easily make AUs about said characters), the loudness of its ship wars, controversies on the redeemable potential of its base breaker characters, the pronouns and gender identity of the player character, and so on. Not helping these was that at the time the game had a Friendly Fandom situation with Homestuck, itself prone with a similar amount and types of wank. Evidently, the fandom has calmed since, but the stigma remains. On the hatedom side, if you even bring up the game in certain forums, even if the mention is actually relevant to the issues discussed, you will get bullied and called a troll for "ruining" whatever the discussion was.
  • The Fallen Child's nature is left deliberately ambiguous for the player to decode, but that hasn't stopped some theorists from trying to force their views on others. The Fan Wars can become quite bloody.
• Heartwarming in Hindsight: Toriel was already heartwarming by default, but when you later discover that the reason why Toriel treated you as her child is because she's had children before and sees them in you. Also, she lives in the sealed ruins because this is where both her children's remains are.
• Holy Shit Quotient: The very *existence* of the sequel Deltarune was this.
• Idiosyncratic Ship Naming: "Fishbones" for Papyrus/Undyne, "Kingdings" for Asgore/Gaster, and "Fontcest" for Sans/Papyrus.
• It Was His Sled: Many things from this game qualify due to the nature of it, but most particularly, the fact that there are even routes in the first place. The game intends for you to play it through normally, then strive for one route or another to see what can happen within the game's parameters, but due to liberal discussion about routes and the many details of the storyline, most people introduced late to the game already know to probably play the Pacifist route first.
• Jerkass Woobie: Once one learns exactly why he is such a jerk in the first place, it's easy to feel sympathy for Flowey.
  • The Fallen Child maybe. Many fans have speculated They have some tragic past or Freudian Excuse. Like with everything involving the Fallen Child, this is unclear.
• Magnificent Bastard:
  • Mettaton is a ghost monster given a robotic body by Dr. Alphys, as well as a massive star in the Underground for his TV shows and music. Gaining a love of humanity, he began manipulating Alphys while setting up traps for the humans, as well as using either manipulating or hiring other monsters into fighting Frisk. And then revealing his true plan to take Frisk's soul and go to the surface himself.
  • Flowey the Flower had the powers of the player and the ambition to gain the human souls to become god, but could never get past Asgore. Thus they follow and wait for the Fallen Child/Frisk to defeat Asgore for him allowing him to take the souls. On the Pacifist route, now believing Frisk to be his long lost sibling, Flowey manipulates Papyrus into bringing all the monsters into one area. Before taking all of their souls to use with the human souls, becoming a god and reclaiming his original form Asriel Dreemurr.
• Most Terrifying Sound: Flowey's laugh quickly becomes one.
• Player Punch: The game doesn't spare a bit into punching you in the feels.
• Polished Port: The PlayStation 4 and PlayStation Vita versions had to make many technical changes to account for both the differing hardware and Sony's guidelines. And yet, for the most part, they managed to maintain the overall experience of the PC original.
• Praising Shows You Don't Watch: When considering for the prevalence and passion of the Undertale fandom, it's hard to make sense of how many fans have actually played the game. Given how the characters deeply overshadow the gameplay, this is understandable.
• Rescued from the Scrappy Heap: The months since the game's release have seen an increase in the use of the Comic Sans and Papyrus fonts, which before were two of the most hated fonts of the lot.
• Ron the Death Eater: Both Asgore and Toriel get this. Asgore is often seen as an irredeemable tyrant for his murder of the six children. However, the game shows that Asgore didn't like doing so and is ultimately an Anti-Villain. On the opposite end of the spectrum, Toriel is called by critics of her to be a "traitorous bitch" for leaving Asgore despite the fact that Asgore's plan, even if he came to regret it, was to commit genocide. Also, she's often insulted for "kidnapping" the children despite the fact that there was nowhere else for the children to go, and if she let them leave, they'd be killed by underground forces. Bizarrely, she's BOTH insulted for that and "leaving them to die", meaning that if she doesn't keep you from leaving, she's a kidnapper, but if she does, she's a sociopath. Accusations of her being a hypocritical coward further fall flat as in several endings she returns and leads the underground showing that she would have led her people if not for the war
• Scrappy Mechanic: Prior to an update that adjusted their color slightly specifically to address these complaints, blue attacks were this for colorblind players who couldn't see green or red, as the shade of cyan used was (respectively) just a hair darker than and all but indistinguishable from harmful white attacks. Considering many bullet patterns require the player to think quickly in order to distinguish between blue and white and avoid taking damage, this was a fairly major issue.
• That One Boss:
  • Mettaton EX can come to this if one is doing a Pacifist run because of the Ratings mechanics.
  • Sans in the Genocide route. Specifically stated in-universe to be intended to cause Rage Quit, and it shows.
• That One Level:
  • Hotland. In compensation to have one of the best overworld themes of the soundtrack, it brings an insane amount of downright frustrating puzzles, surprisingly stronger monsters, and of course Mettaton.
• They Wasted a Perfectly Good Plot: Some believe the idea of getting a better ending by not killing monsters on a second playthrough could have been executed better. Because the first friendly character you meet unsubtly encourages you to not fight the monsters, and the only one who encourages you to kill monsters is rather Obviously Evil, some feel that the impact of killing enemies and facing the consequences of such is lost; these people feel that if the game allowed you to kill enemies before meeting Flowey and Toriel, the impact of having killed innocent beings would have been greater.
  • It's minor, but it's stated that monster souls were absorbable, but this doesn't feature in the game. Just imagine on a Neutral or Genocide run where you get Undyne or Toriel's powers and use them in battle, perhaps hear their dialogue either begging the player to stop on a Genocide route or slowly forgiving them on a Neutral one.
• Unpopular Popular Character: Papyrus. In the game, he somehow has a negative follower count on the Undernet, and his only guaranteed friends are Undyne and his brother. In real life, he's one of the most popular characters in the game and very few people dislike him.
• The Woobie: Alphys to the point where there's even a full-article-length entry about it on ATT's douchebag mother site TV Tropes.
  • On the Genocide route, Papyrus... dear god Papyrus.
• Unintentionally Unsympathetic: A minor one, but the Fallen Child saying the player had a "perverted sense of morality" seems to be an attempt at Even Evil Has Standards; instead, whether you interpret this as because they kill for power not fun or simply for doing genocide twice, it falls flat as they both hijack the Pacifist route ending no matter how many times you view it and had no reason to give the player a false sense of choice over to erase the world or not other than For the Evulz, so it just makes them look like a hypocrite (unless it was meant to be a compliment).