Undertale/YMMV


 * Alternate Character Interpretation: Hoo boy. Just about everyone invites this to some degree, though the biggest offender is easily the Fallen Child.
 * The reason why
 * And perhaps the biggest one:
 * Some fans recently have taken a third option with the Fallen Child,
 * Dr. W.D. Gaster even more than the Fallen Child, as his actual existence is mere speculation.
 * 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.
 * Anticlimax Boss:
 * Mettaton NEO. He looks strong, but.
 * 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 . 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.
 * Alphys, however, is even more decisive for similar reasons as Asgore: . 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. . Not helping matters is the relevation that ?
 * 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.
 * 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 ...
 * 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 kill or be killed mindset, murders, and . 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.
 * 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 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 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 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.
 * 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.
 * 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's 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.
 * 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 iredeemable 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 "traitoras 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.
 * 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.
 * 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.
 * 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.
 * 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.