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Undertale the Musical is a musical adaptation of Undertale created by Man on the Internet (also known as Alex Beckham). With 41 songs and a diverse cast, it follows the True Pacifist Route of the game.

All of the musical's songs can be found here. The full musical as one video was livestreamed on YouTube and can be found here. Man on the Internet has also made videos for a Genocide package (but not a full musical, as it doesn't contain dialogue between songs), which can be found here.

It's followed up by Deltarune the (not) Musicalnote , a series of songs based off of the soundtrack of Undertale's successor, which can be found here. Similar to the Genocide package, there is no dialogue between the Deltarune songs, and, like the title says, they're not part of a full musical. Despite a longtime refusal to cover fanmade content (a few songs from the Genocide package nonwithstanding), covers of the fanmade prequel Undertale Yellow also started in 2024, once again not as a full musical.

Also, be warned that this will contain unmarked spoilers from the original games.

"If you climb along this trail, you will hear the Undertale..."

  • Adaptational Alternate Ending: The Genocide Package has a bonus episode "Entry Number 17 - Dark Darker Yet Darker" that ends with W.D. Gaster erasing Frisk and saving the world rather than merely having the world be destroyed by Chara.
  • Adaptational Badass: Mettaton NEO in the Genocide Package. In the actual game, he can't attack you, and dies in one hit. Here, he doesn't even give Frisk a chance to attack for most of the battle and puts up a huge fight. He still goes down in one hit, but he makes Frisk work for that hit.
  • Adaptational Dumbass: The Snowdin K-9 unit, compared to the original. They could already be neutralized fairly easily in the gamenote , but they're even less competent here. In their song, "Dogs Approaching", all five of them attack the human at once and they still somehow blow it. Even Papyrus gets fed up with their lack of professionalism.
  • Adaptational Heroism: Rather than his death being treated as a joke, in "Power of Neo" in the Genocide Pack, Mettaton NEO actually gets a chance to fight to protect those he cares about. He becomes a true hero to protect monster-kind and gives it his all, accepting his death if it means everyone else survives.
    Mettaton NEO: If this is the last time we meet, Then I shall accept my defeat, if it means my people are safe my people are free~!
  • Adaptational Intelligence: In the game, nothing indicates that Lesser Dog and Greater Dog have an intelligence level that's anything more than above average for a regular dog, and neither of them even speak, unlike the other dogs. Here, while the K-9 Unit as a whole seem to have suffered a drop in intelligence, both Lesser Dog and Greater Dog seem to be just as intelligent as the other three members, and they both have actual dialogue.
  • Adaptational Jerkass: Downplayed. Papyrus is still the Kindhearted Simpleton he is in the games, but he is a tad quicker to lose his temper with both Sans and the Royal Guard, repeatedly shouting at the former to stop messing with his music and impatiently dismissing the latter as "amateurs" when they fail to capture Frisk.
  • Adaptational Villainy: Muffet. While she's definitely one of the more selfish and aggressive characters in the original game, she did at least reason it with thinking the human killed spiders. Here, she openly admits to wanting to kill them for much less sympathetic personal reasons, and even shares her Villain Song with Flowey of all people. Also, rather than agreeing to spare Frisk, she's chased away by Alphys.
  • Adaptation Deviation:
    • Chara is shown to have not fallen in the year 201X and instead in more ancient times as seen with the lack of a year during the opening and the humans who attacked Asriel wearing medieval peasant clothing.
    • As demonstrated in the song "Undertale", there were already golden flowers in the Underground, whereas in the game, they only started appearing there after Toriel left Asgore.
  • Adaptation Personality Change: In the Genocide Pack, Sans makes MUCH clearer just how much pain the Fallen has caused him with their actions, screaming and forcing out his lyrics for "Megalovania" as if he's suffering a complete meltdown, unlike his canon Tranquil Fury. This was a conscious decision on the part of the musical's actors and developers.
  • Adapted Out:
    • Mad Dummy does not appear in this musical, and neither does the Dummy in the Ruins; Toriel has Frisk practice with Napstablook instead, and after Undyne destroys the bridge followed by the interlude with Chara and Asriel, Frisk wakes up thanks to Napstablook's phone ringing. Lampshaded in the Creative Closing Credits where the text under the Mad Dummy reads "Sir Not-Appearing-In-This-Musical".
      • Mad Dummy has their own song now, though it's considered a standalone and not officially part of the musical.
    • While most of the other miniboss fights are showcased in the musical (aside from Mad Dummy), the one with Royal Guards 01 and 02 is not. The Creative Closing Credits note, with a sad emoticon, that "no one wanted a song for them".
    • The Temmies also do not have a role in the musical, despite their popularity amid the fandom. One does, however, appear in the artwork for "Reunited".
  • All Musicals Are Adaptations: Albeit one that hasn't premiered on stage as an official performance with the cast, though some fans have performed it with Alex's permission (mostly).
  • Always a Bigger Fish: The Fallen pulls this on Frisk in the Genocide package, and then Gaster one-ups them.
  • Ambiguous Gender: Frisk and Chara, especially the former. Sans refers to Frisk as "Man" a few times (though that could have been more general) and "attaboy" once during "It's Raining Somewhere",note , and both Frisk and Chara have feminine voices, though they are still generally referred to with gender-neutral pronouns, and Undyne very obviously has no clue what their gender is.
    Undyne: Quit running and face your death like a man... woman... child?
    • Averted with the human SOULs, unlike in canon. The cyan, blue, and green SOULs are female, while the orange, purple, and yellow SOULs are male.
    • Subverted for Deltarune The (Not) Musical; Kris is decidedly masculine unlike how the character in the game proper is left ambiguously gendered. Alex noted elsewhere that this is his own personal interpretation of the character, and made it very clear he won't tolerate anyone fighting him or others about it on his videos, since it can be a volatile topic.
  • Anti-Climax: The Genocide Package seemed poised to end like this. Following the blood pumping rendition of "Megalovania", "But Nobody Came" is a slow, ominous, minimalist tune that drives home the sensation of empty victory the Genocide run brings. However, it ends up subverted by "Dark Darker Yet Darker", which sends off the Genocide Package with a chilling yet awesome confrontation with Dr. Gaster that brings about a Bittersweet Ending. Double Subverted, however, since since "Dark Darker Yet Darker" was not included in the full Genocide package video, strongly indicating it's not canon to the story.
  • Arc Words:
    • "End this sorry tale" pops up in several songs, with several variations.
    • "So much blood, so much pain." sung at several points by Asgore to the opening bars of "Bergentrückung". Lampshaded and poked fun at in the credits of the full musical where Asgore's credits text says "Sang that motif like 50 times".
    • “Sunlight” or “daylight” appears in both the musical proper and the Genocide package, referring to the Underground’s desire to reach the surface.
  • Artistic License: In the Genocide Package, Frisk is using a knife the entire way through, despite the Real Knife being unobtainable until New Home and the Toy Knife being quickly outclassed. However, on top of this discrepancy being common in fanart anyway, some of the boss fight artwork would have been less dramatic if they were shown with the weapons the player would conceivably be using at that point in the game — just try imagining Frisk fighting Undyne the Undying with ballet shoes or Mettaton NEO with either a frying pan or Pistol-Whipping.
  • Art Shift:
    • Waterfall uses CGI art rather than the usual 2D art.
    • Battle Against a True Hero intersperses the gameplay footage of the Undyne the Undying battle from the game proper with footage of the fight from a classic Doom mod of the Genocide path.
  • Asshole Victim: It is heavily implied that Gaster drags the Fallen human off to the void in "Dark Darker Yet Darker". It's an understatement to say that they absolutely deserve that fate.
  • Badass Boast: "Dark Darker Yet Darker" contains a few good ones by Gaster.
    Gaster: I will stop your evil plan,
    I've become a boogeyman
    Haven't you heard to beware
    the doctor who speaks in hands?
  • Big Bad: As in the game, Flowey, Asriel’s evil reincarnation, seeks to manipulate Frisk into killing Asgore so he can get the SOULs and destroy everything, and even gets an expanded role to showcase that.
  • Big Bad Duumvirate: In the Genocide package, as in the game, Flowey teams up with Chara, the first Fallen Child, to kill everyone in the underground and steal their power to destroy humanity.
  • Bittersweet Ending: The Genocide Package, contrasting its status in the game. Dr. Gaster appears after Chara makes their "deal" and emerges victorious, with the implication in Gaster's lyrics that the world will be restored and reset without Chara reviving; however, because of Chara being consumed by the void, a reset is likely to not include Frisk, meaning the sad saga of the underground will repeat again in the future with another 7th child. May be subverted, however, since "Dark Darker Yet Darker" was not included in the full Genocide package video, strongly indicating it's not canon to the story.
    • Played with in "An Ending", which is basically the same as the Neutral ending in the game in its literal events, but the tone heavily plays up how the monsters are still trapped underground, lamenting their king and trying to hold on to their hopes, even if the human made it out and their friends are happy to hear it.
  • Bloodstained Glass Windows: Depicted per the game, commented on in the lyrics to "Megalovania"; when it comes to a fight against Sans near the end of the Genocide package, he refers to "defiling this sacred place" in his efforts to stop the Fallen.
  • Bread, Eggs, Milk, Squick: "Attack of the Killer Queen" has the line "College Vacay, Skateboarding Games, and December Holiday", the last of which refers to Noelle's missing sister. Although the reference to "College Vacay" isn't exactly lighthearted either, since it likely references Kris's yearning for Asriel to return from college, although the reference to Dess is way more dark.
  • Breaking the Fourth Wall: Sans does this quite often, true to the game, but Papyrus also joins in the fun during "Bonetrousle" and "Let's Dating Love."
    Sans: you gonna tell that to the orchestra? [under] you calling them incidental?
    • Also Chara/The Fallen's speech at the end of the Genocide package.
  • The Character Died with Him: Played with In-Universe. After Mettaton NEO's death in the Genocide package, Alex, Mettaton's voice actor, is absent from the Patreon slide.
  • City Shout Outs: Mettaton has a habit of asking the crowd, "Are you alive, Hotland?", which is definitely meant to evoke a similar effect. At the end of "Death by Glamour", his last thought on the matter is a straight, "I LOVE YOU HOTLAAAND!"
  • Colour-Coded for Your Convenience: When the 6 human SOULs start singing different lines in Your Best Nightmare, the subtitles have the colour(s) of the SOUL(s) that sing them.
  • The Comically Serious: Most of the artwork shows Frisk with the same flat expression they have in the game, resulting in this effect in certain scenes like Mettaton's opera or Undyne's cooking lesson.
  • Composite Character: In addition to filling their own role from the game, Napstablook also takes the place of the training dummy in the Ruins.
  • Compressed Adaptation:
    • Hotland and the CORE are merged into one location; while the latter's song is used, monsters from the former are shown to represent it in the artwork and the endslate for the song (though one of the Core's monsters, Astigmatism, does show up in the artwork for "For the Fans").
    • "Your Best Nightmare" forgoes the Victory Fakeout of the Photoshop Flowey fight, as the Souls rebel and attack Flowey before he can start using his SAVE file.
  • Creative Closing Credits: The text underneath each monster in the first part of the credits is altered, and the "Special Thanks" part is used to credit the cast, crew, patrons, and other contributors of the musical.
  • Crowd Song: Parts of "Death by Glamour" and "Spear of Justice" fit into this.
  • Curb-Stomp Battle:
    • Gaster dishes one out to the Fallen. Not once in the 'fight' does the Fallen get anything resembling meaningful offense in against him.
    • As in the game, Asgore in the Genocide package goes down in a single hit to a sneak attack.
  • Curb Stomp Cushion: Mettaton NEO still goes down in one hit, but unlike in the game proper, that one hit doesn't come easy, and some of the text implies he still manages to wound Frisk.
  • Curse Cut Short/Astonishingly Appropriate Interruption: In Mad Dummy's standalone song:
    Mad Dummy: Rage twitch! Rage itch! Time to die, you little-
    Chorus: DUMMY!
  • Dark Reprise: As well as songs that were already dark reprises in the game (such as "Waterfall" for "Ruins"), "Metal Crusher (Reprise)" is a semi-tone lower than the earlier number in the musical and covers the moment where Mettaton reveals that everything in Hotland apart from the spiders was set up by Alphys before turning on her and trying to kill the human for real.
    • The Genocide Package dips into this a fair amount. For example, "Ruined" is a slower, more somber version of "Ruins", to accommodate for the fact that the main character is now slaughtering everyone.
    • "Floweytale" is this for "Undertale", as Flowey tells how he descended into madness over time and his breakdown when he realizes he's not safe from you.
    • For "Deltarune the (not) Musical", "The World Revolving" gets turned into this for "Don't Forget", with Jevil inverting and mocking that song's hopeful tones.
  • Deadpan Snarker: Gaster's response to being stabbed? "I can see you didn't miss me."
  • Death Song: "Undertale" for Chara and Asriel. "His Theme" is a variation, as it involves Asriel knowing he is about to revert back to Flowey, and notes that his time is nearly up. "For the Fans" is another variation, since even though Mettaton isn't dying, but simply losing his battery power, the Ominous Visual Glitches certainly make it come off like he's dying.
    • As for the Genocide package, specific characters get specific songs, including "DeTermination" for Toriel, "Papyrus Believes in You" for Papyrus, and "Ruined", "Evacuate", and "But Nobody Came" for the monsters.
  • Don't Explain the Joke: There is one line that is given an annotation:
    Undyne: Hey there human- woah! Did you get a new phone? The signal sounds like I'm right there with you!
    [cue brief pop-up that reads "the joke is that on stage, she probably is"]
  • Dragged Off to Hell: It's implied that Gaster does this to the Fallen at the end of the Genocide Package, dragging them back to the Void with him.
  • Eldritch Abomination: Omega Flowey's status as one is played way straighter than even the game thanks to the visuals presented.
    • W. D. Gaster could count as this as well, considering his Mind Screw of a fight.
  • Evil Is Hammy: Flowey really lets loose the ham when he's not being Faux Affably Evil, particularly as Omega Flowey where he's very clearly Drunk with Power and enjoying every minute of it.
  • Explain, Explain... Oh, Crap!: When Papyrus reprimands Sans for making dog and bone puns, he explains that the human's probably almost at Snowdin Town and runs off in a panic.
  • Failed a Spot Check: The K-9 unit of the Royal Guard has a bad habit of this, as them losing sight of the human is a Running Gag throughout the "Dogs Approaching" segment. By the end of it, Papyrus is utterly fed up, remarking that this is why he chooses not to work with "amateurs".
    Sans: it's right there.
    Dogs: Oh…
    Doggo: Don't ask questions you don't want to know the answer to…
  • Fallen Hero: Implied to be the case with Frisk in the Genocide package as "Megalovania" implies that Sans can remember the Pacifist ending.
    • More explicitly the case with Chara—their song "Star" is basically them lamenting their original life before saying that they have accepted that all they can do now is embrace what they've become.
  • Foreshadowing: Mettaton's NEO form is referenced several times in the pacifist musical:
    Mettaton: Don't touch that dial, put on a smile!
    Mettaton: The love of my fans is almost giving me wings!
  • The Fourth Wall Will Not Protect You: Inverted. Mettaton goes out of his way to reassure the audience that they're safe from the bombs.
    Mettaton: Don't worry, folks, this is all part of the show! (You might have gotten some subtle hints beforehand.)
    If they go off only the kid's gonna blow!
  • Funny Background Event:
    • In the background of one of the flashback scenes of "Undertale", one of the angry villagers is wielding an entire barrel of alcohol.
    • One scene in "Reunited" shows Temmie in the background, upside-down and in the air.
  • Giant Space Flea from Nowhere: Gaster appears in a bonus track after the Genocide Package.
  • Given Name Reveal: "My name... is FRISK!"
  • Gratuitous German:
    • "Bergentrückung" includes the title in its lyrics, mostly in the background.
    • In "DeTermination", the deceased Ruins monsters sing "Halte dich fest an deiner Entschlossenheit" (which roughly means "hold fast your determination") in the background.
  • Harsh Vocals: Parts of "Megalovania" have Steel practically roaring with a Type 1 or 2 Metal Scream.
  • Hero Antagonist: Just about every monster in the Genocide Package counts, though special mention goes to Mettaton NEO, who is actually trying to stop the human instead of buying time like in Undertale, and W.D. Gaster, who comes back from the dead to avenge his sons.
  • Heroic Mime: Frisk doesn't say a word through most of the musical despite being a main character. The silence is finally broken by "Hopes and Dreams", and they subsequently hold a full two-sided conversation with Asriel.
  • Hoist by His Own Petard: Gaster kills the Fallen Child by making them impale themself on their own knife.
  • Impaled with Extreme Prejudice: How Asriel's death is depicted in the titular song, "Undertale".
  • Incoming Ham: Mettaton makes his grand entrance by bursting through the wall and shouting "HEEERE'S METTATON!"
  • Ironic Echo:
    • In Your Best Nightmare, Flowey has the line, "Dance to my puppet strings." At one point after the human souls rebel against him, they sing, "Now dance to OUR puppet strings."
    • In Deltarune, the lyrics "Welcome to the internet, the best hasn't happened yet", part of the chorus of "A Cyber's World", reappear in Queen's Villain Song.
  • I Will Show You X!: When Papyrus tries to get the human to do all of Undyne's more romantically minded ideas with Alphys rather than just say hi to them because it'd be "flattering". Undyne's response is "I'll show you flattery," after which she apparently gives him the "Flattery Suplex".
  • In Memoriam: "Evacuate" has a credits dedication to Moony, the artist who made the artwork for all the pacifist songs and the genocide one until "Evacuate"
  • Large Ham: Mettaton and Undyne yell out just about every line.
  • Last-Second Word Swap: A subtle one appears in "Dogs Approaching":
    Where'd the human run off to? / Weren't you keeping watch?
    No, this snow is freaking awesome! / Can I sniff your- What?!
    • While more of a "Last Second Sentence Swap", Undyne's line when she's chasing the human and the human hides in some tall grass counts.
      "If it weren't for that grass, I'd kick your- ...I mean... If it weren't for that grooty, I'd kick your booty! Don't ask me what a grooty is!"
    • The standalone song "Dummy!" contains one, courtesy of the background chorus.
      All of this yelling
      Screaming and swelling
      You, little human, can go straight to Hell-ing!
      Rage twitch! (Dummy!)
      RAGE ITCH!!! (Dummy!)
      Time to die, you little- (Dummy!)
  • Late-Arrival Spoiler: The musical assumes the viewer is already familiar with the original game, with the opening listing the cast for all of the major characters, including the Walking Spoilers. Best exemplified during "Your Best Friend", where Flowey casually reveals what "LOVE" really stands for, which is something you don’t learn until the end of a regular playthrough.
  • Leaning on the Fourth Wall: During a scene with Sans, Papyrus, and Undyne watching Mettaton's show, Sans says "It's the middle of a show." This scene comes about halfway through the video's run time.
  • Letting the Air out of the Band: Happens on more than one occasion, such as when Papyrus gets a call from Undyne after explaining how she isn't likely to take his friendship with a human well.
  • Lyrical Dissonance:
    • The background music for most of Flowey's songs sound like they belong in a children's TV Show. The lyrics most certainly do not.
    • Similarly, in Deltarune the (not) Musical, "THE WORLD REVOLVING" sets the eponymous jaunty circus-style tune against some very disturbing lyrics showing just how much Jevil's mind has utterly snapped. It's compounded by the fact that his tone is one of manic glee throughout the whole thing.
      Jevil: There's a light inside your soul
      Slowly shrinking in the cold
      From the truth deep down you know
      And yet darker we will go!
  • Mad Hatter: Downplayed, one lyric of "Dark, Darker, Yet Darker" implies that Gaster, following his return from the CORE, might not be entirely there mentally speaking. He doesn't mind, though.
    Gaster: The doctor is insane. I have bugs in my brain. But the truth still remains: you won't be entertained.
  • Meaningful Echo: Several:
    • In "Death By Glamour", Mettaton says that he feels like the love of his fans is giving him wings to fly from the underground. In "Power of Neo", he sings "Raising my face to the sky, giving me wings and the power to fly" in reference to his genuine determination, strength, and true heroic desire to protect everyone.
    • In the Pacifist Route, part of "Spear of Justice" has Undyne say "Real heroes never fear, real heroes laugh at death", which in context was really bathos. In "Power of Neo", Mettaton reprises this line in a much more solitary and serious tone to emphasize his brave last stand.
    • In "CORE", lyrics say "Through the fires and the flames you will see something very strange". While it talks about the monsters hunting the human for Mettaton, Gaster rephrases these lines as "Through the fire and the flames they've forgotten my name". Quite fittingly, since the musical establishes that Gaster fell into the CORE.
    • In "Your Best Friend", Flowey sings at one point "You fell down now I'll have fun." Gaster repeats this in "Dark, Darker, Yet Darker", doubling as a Stealth Pun.
  • Mind Screw: Gaster's confrontation with the Fallen is made of these, highlighting that Gaster might have returned, but not as something remotely resembling what he once was. The biggest one is when the Fallen Child seems to have landed a killing blow, only for it to be revealed they somehow impaled themself.
  • Mood Whiplash:
    • Almost immediately after the intense, upbeat, and very hammy "Death By Glamour", we get the slow, emotional "For the Fans", which has all the trappings of a Death Song except for the fact that Mettaton technically isn't dying.
    • Directly following "Reunited", a slow song that somberly echoes the various themes of the musical and concludes the story, is the upbeat "Bring it in, Guys", which is, to paraphrase Alex himself, "the cheesiest curtain call ever."
    • Happened several times in the Genocide Package livestream. First, "Megalovania" was replaced with one of the previously seen parody videos. Then, after the Genocide Package's depressing ending, we got a viewing of "Undertale the Musical Except It Gets Faster And Abuses Your Senses." And then, the first Judgement Hall scene is replaced with the real "Megalovania" at normal speed.
  • Movie Bonus Song: The full version of the musical features one more song that wasn't included in the initial playlist: "Last Goodbye," sung by Asriel over the special thanks.
  • Musicalis Interruptus: The second performance of "Bergentrückung"; Asgore performs it in full the first time around, but the second time, since Frisk is now on the True Pacifist route, he only makes it through the intro before Toriel cuts him off with a fireball.
  • No-Sell: The Fallen slices Gaster in half, but he barely seems to notice and just reforms.
  • Oblivious to Love: Undyne could not possibly be more blatant about her crush on Alphys, but Alphys is convinced Undyne only thinks of them as friends. Undyne, for her part, also thinks her feelings are a big secret, but even Papyrus notices.
  • Oblivious to His Own Description: An example that's not Played for Laughs. One of the verses in "Hopes and Dreams" has Asriel taunting Frisk, beginning with "You think you are something special? You're just a kid playing pretend!" Frisk then proceeds to turn the exact same verse against him.
  • Ominous Visual Glitch: In "For the Fans", as Mettaton gives his final speech, the visuals and audio start glitching, getting worse as he continues speaking, as a way of showing that he's running out of battery life.
  • Opening Chorus: "Once Upon a Time".
  • Overly Long Gag: Shortly after Mettaton's introduction, Alphys repeatedly goes back and forth into her bathroom 3 times for about 5 minutes. To fill in the time, Frisk tries out their new phone, and Muffet makes her inexplicable debut.
  • Overly Narrow Superlative: At one point in the fight against Papyrus, he mentions that it's the longest a human has ever lasted against him. Sans immediately points out that the fallen human is the only one he's met so far.
  • Painful Rhyme:
    • Used for comedic effect in the standalone song "Dummy!". In one verse, he attempts to rhyme "again" and "vain" without even trying to make the words sound alike. Another has him rhyming "rage twitch" with "rage itch". The most blatant example would be the verse "All of this yelling/Screaming and swelling/You, little human, can go straight to Hell… ing!"
    • Also used for comedic effect in Rouxls Kaard's song in Deltarune, rhyming "dungeon" with "for fungeon" and then responding to the viewer calling out the bad rhyme in the next line. The first half of his song also has a few due to his Ye Olde Butcherede Englishe, such as "Now thou seest / the power of meest".
    • In-Universe example during Papyrus's introduction, when he rhymes "gone" with "one."
    Sans: That doesn't rhyme.
  • Papa Wolf: Part of Gaster's reason for attacking the Fallen is to avenge Papyrus and Sans, his sons. He succeeds.
    Gaster: You fell down, now I'll have FUN, for the sake of everyone, to avenge my fallen sons, YOU CAN'T STOP WHAT HAS BEGUN!
  • Parental Love Song: "Home" is one of these from Toriel's point of view; the lyrics are reprised in "Reunited" as a duet between Frisk and Toriel, with some contributions from Asgore.
  • Patter Song: A lot of Mettaton's lyrics, especially those in "Metal Crusher" are sung incredibly quickly, with impeccable diction and timing.
  • Poke the Poodle: In Deltarune, Lancer's best ideas on how to be a "bad guy" are drinking from a lake, eating someone else's birthday cake, digging a hole, and digging a bigger hole.
  • Pragmatic Adaptation: A lot of elements from the game are changed or outright removed to fit with the more streamlined, movie-like feel of a musical. For instance, the audience is shown Asriel right from the start, though it's not clear who he is until the climax. Flowey also has more of a presence as the main villain. Incidental characters like the Dummy are cut, allowing characters like Napstablook to have a slightly larger role. Lines referring to the story as a "game" are changed to refer to it as a "show." Most notably, the Multiple Endings thing is removed almost entirely, but Resets are not — so we only see the most common "Neutral-Pacifist" ending and the Golden Ending, as the musical only covers the Pacifist route. Also, the Reset is presented as the video rewinding backwards instead of resetting a game file.
  • Pungeon Master: Sans is this as much as in the game, and Toriel is more so.
  • Reality Warper: Gaster seems to be this, throwing the Fallen Child through a Mind Screw series of dimensions and somehow making them stab themself.
  • Red Baron: The Mountain King for Asgore.
  • Religious Horror: Not explicitly, but Jevil's lyrics in Deltarune The (Not) Musical's "THE WORLD REVOLVING" have some undoubtedly creepy religious overtones:
    Jevil: All around the game of life, we laugh we play and revel
    Don't fall off the carousel or else you'll meet the devil
    All the gathered sin begat the father to the child
    What a mess we're in but now the joker's running wild!
  • Set Right What Once Went Wrong: The sole reset shown is Frisk going back in time to try and get the Golden Ending after missing a part of it the first time around.
  • Shout-Out:
  • Shrug of God: Mentioned by name by Alex on Tumblr when asked why Asgore says "I have seen my son again" at the end of the musical.
  • Sophisticated as Hell: Queen in "Attack of the Killer Queen", as in the original game:
    Queen: Raise A Glass / While I Thrash Your Ass / I'm The Head Of Class / And You're Peons
  • Stealth Pun:
    • Gaster comments that the Fallen Child "didn't miss [him]." Meaning the Fallen wasn't sad that he was gone... and also that they literally didn't miss him, since they landed a hit on him.
    • Later on, Gaster sings "You fell down now I'll have FUN", alluding to Gaster's connection to the game's "Fun" value.
  • The Stinger: The end of every video has the main subject of the song advise the viewer to subscribe and turn on notifications.
  • Stylistic Suck:
    • Mettaton's falsetto in the opera portion combines this and Large Ham. It has to be heard to be believed.
    • The art for "When's Megalovania?" as it's not part of the musical — it's a joke song in response to those who keep asking for "Megalovania" even though the musical is about the Pacifist Route.
  • Sudden Downer Ending: Zig-zagged. Gaster manages to resurrect himself to stop the Fallen after the end of the Genocide Package and succeeds… but the full Genocide Package video does not include "Dark Darker Yet Darker", heavily implying it's not canon to the package.
  • Suddenly Speaking: During "Hopes and Dreams", Frisk actually starts singing, having spent the entire musical being silent until that point. They then sing for the rest of the songs and appear in The Stinger for "Bring It In, Guys".
  • Summon Backup Dancers: At one point during "Bonetrousle", Papyrus shouts, "BRING OUT THE BACKUP DANCERS!"
  • Take That!: Underfell the Musical. Literally the entire video is an abridged retelling of the play but with all vocals turned down, the color pallet resembling something out of a Virtual Boy game, and shoehorning Megalovania at the end at where the Judgement Hall scene would be. The description says it all:
    Wow look at how original, creative, and "great" an idea this is, I sure do enjoy "Literally just Undertale but everyone is evil and has no recognizable character traits anymore, except it doesn't matter, the only ones we focus on are Sans and Papyrus because I, as an adolescent writer of AUs and fanfic, want to explore my sexual awakening through these fictional skeletons but only if they're edgy and don't resemble the original in any way." And now, the Man on the Internet presents - a musical that is boring, and goes completely against what Undertale tried to teach!
  • Then Let Me Be Evil:
    • "Star". See Villainous Lament below.
    • From Deltarune, "Vs. Susie" is one in song form... but she manages to talk herself out of it by the end.
    Susie: Everybody's sayin' "Susie's just a common brute" / so I guess that that's the truth / I see nothing else to do
  • They Called Me Mad!: Comes up in "Your Best Nightmare":
    Flowey: Everyone said I'm insane / EVERYBODY DIES IN PAIN
  • Things Man Was Not Meant to Know: Gaster implies he knows a few of them.
  • Triumphant Reprise:
    • "Fallen Down (Reprise 2)". The first rendition was loving, as Toriel welcomed Frisk to the Ruins and offered to be their guide, but the first reprise was very bittersweet as the two parted ways; the second reprise has them finally meeting again.
    • "Reunited" is one of these for both "Home" and "Once Upon a Time".
  • Trrrilling Rrrs: Papyrus.
  • Villainous Breakdown: Asriel gets hit with a bit of Sanity Slippage in the middle of "Hopes and Dreams", as the song itself drops all rhythm and melody while Asriel takes a dip into Omnicidal Maniac territory:
    "Don't you understand, Chara? I am the God of Hyperdeath! IT'S KILL OR BE KILLED! AND EVERYONE WILL DIE AT MY HAND! [Beat] Why are you still standing? WHY ARE YOU STILL TRYING TO STOP ME, CHARA?!"
  • Villainous Lament:
    • While "Bergentrückung" is a pretty epic Villain Song, it also highlights Asgore's status as an Anti-Villain with him at one point lamenting how he'd love to spare the human and live with them and Toriel as a family, but he's come too far to stop now and expressing his guilt over his actions.
    • "Your Best Nightmare" elaborates on Omega Flowey's canon one. During the second half of the song, as the human SOULs turn against him, Omega Flowey becomes more frantic and desperate in disbelief.
    • "Star" from the Genocide Package expresses Chara’s troubled emotional state. They state that at some point, they tried to be good, and yet their best efforts (their Thanatos Gambit) failed. They have lost all hope of finding redemption and a happy ending. In LOVE and their mindless march towards oblivion, Chara finds agency and an escape from their pain.
      Chara: No hopes, no dreams, I have nothing. Death is all that can define me.
  • Villain Song: Quite a few. Flowey gets "Your Best Friend" and a reprise, "Your Best Nightmare", and shares "Spider Dance" with Muffet. Asgore gets "Bergentrückung". Asriel gets "Hopes and Dreams". Undyne has "Spear of Justice", and Mettaton gets two renditions of "Metal Crusher", the "Mettaton Medley", and "Death By Glamour". In the Genocide Package, Chara gets "Star". In Deltarune the (not) Musical, Jevil gets "THE WORLD REVOLVING", the King gets "Chaos King", Queen gets "Attack of the Killer Queen" and Spamton gets "NOW'S YOUR CHANCE TO BE A" and "BIG SHOT". Also, if you can call them villains, Lancer gets "Lancer", Susie gets "Susie" and "Vs. Susie", Rouxls Kaard gets "Rouxls Kaard" and "It's Pronounced Rules" and Berdly gets "Smart Race".
  • "The Villain Sucks" Song: "Dark Darker Yet Darker" is basically one by Gaster to the Fallen, when it's not being a Badass Boast and "I Am" Song, especially towards the end.
  • Walking Spoiler: The fact that Gaster's included in the Genocide package at all is a huge twist.
  • Wham Line: "Hopes and Dreams" initially seems like it's going to be another song primarily sung by the current villain (Asriel, in this case) until:
    Frisk: That is not my name!
  • Wham Shot:
    • In the titular song "Undertale", we see Asriel getting gutted by one of the villagers while he was trying to fulfill a promise. Anyone that played the game knows what happens to this character, but that doesn't stop this from being shocking since we never actually see it happen in the game.
    • If you didn't catch the video playbar for "Power of NEO" as your hint that this song wouldn't be like the Foregone Victory Mettaton NEO fight in the game proper, then Mettaton shouting "2.0!" before spotlights cover the battle screen makes it clear that Frisk is gonna have to work a lot harder for this victory.
    • Gaster's signature font appearing and then him rising up behind the Fallen.