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Title Screen


Developer: Toby Fox
Platforms: Windows, Mac OS X, Linux, PlayStation 4, PlayStation Vita, Nintendo Switch
Released internationally: September 15, 2015 (Windows, macOS), July 17, 2016 (Linux), August 15, 2017 (PlayStation 4, PlayStation Vita), September 18, 2018 (Nintendo Switch)

AreasIcon.png This game has unused areas.
DevMessageIcon.png This game has a hidden developer message.
GraphicsIcon.png This game has unused graphics.
ItemsIcon.png This game has unused items.
MusicIcon.png This game has unused music.
TextIcon.png This game has unused text.
DebugIcon.png This game has debugging material.
SoundtestIcon.png This game has a hidden sound test.
RegionIcon.png This game has regional differences.
Carts.png This game has revisional differences.

ProtoIcon.png This game has a prototype article
PrereleaseIcon.png This game has a prerelease article
NotesIcon.png This game has a notes page

What are you doing?

Looking for secrets?

Don't put your nose where it doesn't belong.

Or you might learn something you DON'T like...

Hee hee hee.

Undertale homepage, in the page's HTML code.

UNDERTALE is an indie RPG where no one has to die. Inspired by the likes of EarthBound, Yume Nikki, and Cave Story, it received critical acclaim for its interesting characters, interconnected soundtrack, and twists on standard RPG tropes. Supported by a devoted fan base, for a time, it was hard to avoid this game.

To do:
  • TO-DO page list is located here.
  • A lot of changes to list.
  • A lot of unused text here.
  • A bunch of RG 04 or 03 text was changed, (Supposedly overwritten with RG 01/02 text) confirm this.
  • RG 01/02 has new text if you call Undyne before their battle.
  • Format this page into subpages.
  • Add version differences in the Switch version.
  • Add version differences in the Xbox version. (Including use of unused text...?)
  • The unused text section needs its own subpage.



Read about prototype versions of this game that have been released or dumped.
Prototype Info
Read about prerelease information and/or media for this game.
Prerelease Info
Miscellaneous tidbits that are interesting enough to point out here.

Undertale toby dog.gif
Debug Mode
Unfortunately, there are no insects to be found in this mode.
Undertale-unused spell sprite 2.png
Unused Graphics
There are so many dogs in this game! There's even UNUSED dogs!
Undertale room tundra rollsnow.png
Unused Rooms
From candy pedestals to talkative NPCs.

Developer's Messages

"Don't rip sprites!" Warning

Version 1.00

...and don't even get us STARTED on uploading audio tracks to BrawlCustomMusic!

Please don't upload these huge sprite sheets online. 
Just 'cause most weird things here ARE used, I'd rather them be seen in context first. 
wait like a year 1st...
if you're just ripping normally seen sprites for spriter's resource or smth idc if you use these 2 make it easier tho

abc_1111_0.png contains a crudely-written note addressed to sprite rippers, specifically the ones at the website Spriter's Resource, telling them to wait a year before uploading full sheets online.

Games made with Game Maker, like Undertale, store all of their sprites in big PNG spritesheets, instead of each sprite or character being stored as an individual file. So if one were to upload sprite sheets, the easiest thing to do would be to upload all of the sheets as-is...which would leave all of the spoiler-y sprites on the same sheet as well.

The odd filename was chosen to force it to the top of an alphabetical file listing and make its presence more obvious...which does no good, as the file listing is only visible if the sprites are separated by string name using an external program. Oops. This was replaced in later versions.

Version 1.001

I don't like the b-bepis either!! I-i swear!

you know what i


   the smell
      the texture


Version 1.001 replaces the no-spritesheet request with this vaguely erotic note about "bepis" that is a reference to a man in Moonside from EarthBound who hates the food the player likes. Toby Fox is a fan of EarthBound, and Undertale takes inspiration from the game heavily. Bepis is a silly misspelling of "Pepsi", as well as a word the developers think is silly.

The lack of any real meaning to this new text and the fact that it replaces the earlier request can be taken as permission to begin posting spritesheets, as supported by this forlorn-looking email.

"Don't spoil the game!" warning


Hello. He-he-he-he-have some respect and don't spoil the game. It's impossible to have mysteries nowadays, because of nosy people like you. Please keep all of this between us. If you post it online, I won't make any more secrets. No one will be impressed. It will be your fault! He-he-he-he-ha-he-he-ha-he-he.

This is a sound file of eight text-to-speech voices telling people not to post the game's secrets online. Who in their right mind would do tha— wait a minute...

The odd filename was chosen to force it to the top of an alphabetical file listing and make its presence more obvious. All other OGG-format music and sound effect files present in the game's folder are prefixed with either "mus_" or "snd_".

This file was updated in the 1/20/2016 patch. The updated version takes out pretty much everything that was in the original audio file.

Toby Fox's Message

Part of this game's charm is the mystery of how many options or secrets there are. If you are reading this, please don't post this message or this information anywhere. Or doing secrets will become pointless.
By the way, most of the seemingly unused text/files are used.
If you can find the in-game context for an asset, you can show it off. But if you can't, it probably means you haven't looked hard enough. Anything truly unused I'll probably post myself, later.
Living in a world like this, where people can simply cheat out the answers from the code... your impatience has REALLY damaged you, hasn't it?

This notice is placed at the beginning of the text segment (STRG). It is used in the gml_Script_attention_hackerz_no_2 script, it sets those four strings to the demonx, demony, demonz and demond variables, respectively. (Those names are found between the lines of the message). This script is, obviously, used to warn crackers. It is the first entry in the CODE and SCPT blocks of the data.win file, to increase the chance to be read even further.

In 1.001, however, it has been changed to this:

You have made yourself completely clear.
I, your humble servant, will follow you to the utmost...

The variables have been renamed to demona, demonb, demonc and demond, too. Curiously, the first line from the version 1.00 message is still present along with its associated variable, but has been moved to line 2436 (amongst the messages used for special name choices).

Unused Music


A more orchestrated rendition of "Determination", the Game Over theme. Based on the filename, it was most likely used in a scene related to Asgore.


This funky fresh beat plays exclusively in the "dancing" dog error room. The error room is most easily accessed by messing with your save file.


This unfunky fresh beat plays exclusively in the sleeping error dog room. The error room is most easily accessed by messing with your save file.


Music that uses instruments from Star Fox. Other tracks in the game use instruments from games like Mario Paint, Final Fantasy VI, Chrono Trigger, Mega Man X , and EarthBound, so this wouldn't be TOO out of place.

According to Toby Fox, this song was intended to play when Madjick's magic orbs turn into healing hearts. However, this proved too difficult to implement because the Core's background music continues into monster battles, so it was scrapped.

(Source: Toby Fox)


Another variation of Flowey's boss music. 0:20 onwards is used for scene transitions (however, a sound effect that sounds like that part plays instead of this track), though the beginning goes unheard in normal gameplay.


An unused first part of "Finale". This track is never played, as "mus_f_finale_1_l" plays instead. It is simply a shorter version of the first part of Finale, and it is most likely the game would have restarted at the point where the souls heal you instead of immediately starting on the fight.


Played at the end of the Undertale demo if you kill Toriel in a neutral run, and appears as the last track of the soundtrack (titled "Good Night"), but isn't used in the final game.


A slow, solemn piano rendition of the music played in the Ruins. Possibly replaced with "An Ending."

mus_birdsong's Hidden Loop

mus_birdsong is played when the bird carries you over the gap in Waterfall. However, the music only lasts one loop until it fades out. The file DOES loop properly, however a bit of the music at the end gets cut off in normal gameplay.

Unused Sounds


A voice (presumably Mettaton) grunting.


Flowey says "ahh".


Flowey says "triple".


Flowey says "shake". According to the code for the Asriel Dreemurr fight, this sound effect is partially played in Asriel Dreemurr's "Chaos Saber" attack, but it is not fully used.

Title Screen: Activity Level & 'BALL' sound

Wait, we're categorizing this now?

Press Shift or X five times at the title screen to get this handy screen. Activity Level A is shown if you get a neutral ending. Activity Level B is shown if you complete a pacifist route. Activity Level C is shown if you fight Sans twice or kill him. If none of the requirements are met, "No Information" is shown instead. Typing BALL at the same screen causes a sound to play.

Unused Battles

RG03 and RG04

In the game's files with battle ID 76, there is a fully complete battle set up for two more Royal Guards, RG03 and RG04. RG03 and RG04 are mentioned by Undyne during a phone conversation as switching off with RG01 and RG02 on certain days. Despite this, they were actually cut simply because there wasn't any place they could naturally be put in, according to the artbook.

Their battle revolves around them being old friends who had a falling out, and the Pacifist solution is to get them to make up. The guards themselves are slightly incomplete, both using Aaron's defeated sprite as a placeholder.

Unused Attacks


To do:
Add info on where this is found in the code/scripts

In Sans' battle lies unused attacks. In the debug code, there exists an unused pitch for Megalovania, slowing it down.

There is an unused vertical platforming attack. The first has bones along the bottom, with platforms randomly placed and scaled scrolling from top to bottom. Some platforms wave from left to right slightly as well. To dodge, you are to stay on the platforms and not fall to the bottom into the bones. The next two are sped up versions of this attack, while the last version has extra bones in the middle of the screen to dodge. Because the platforms are randomly generated in size and position, it can be impossible to avoid getting hit.

Another unused attack are vertical and horizontal bones. To dodge, you must maneuver around the bones. There exists two versions of the attack, where it is faster and has a different pattern.

Variants of final attacks captioned as "Hell" versions are within the game's code. The platforming attack with bones and platforms scrolling across the screen horizontally has a varient where the platforms scroll slower. The attack where you have to short hop in between a gap in bones and the one where you hop over a small white bone with a long blue one right after have faster variants.

The last unused attack is a version of the random Gaster Blasters. The sprites for the blasters are squished to be thin, much like one of the final version's variants, although this time the blasters spawn and shoot faster.

Unused Text

Alphys's crush


The script for Mettaton's quiz contains a comment, ostensibly meant to be an in-character quote from Alphys. Specifically, it's placed right after when Mettaton mentions that Alphys names programming variables after her crush, and thus appears to be a bit of an in-joke to people reading the game script.

Mettaton Quiz Unused Questions

What's a pretzel's#favorite color?

This is listed as question "99", despite it not being possible to go that high in-game. The answers, listed 1-4, are:


The correct answer is Yellow.

How bright is#this text?

This is listed as question "14", and once again it is not possible to go that high in-game. The answers, listed 1-4, are:

85% Bright
84% Bright
86% Bright
83% Bright

Despite the question text being the same color as all other questions (#FFFFFF) the correct answer is 85% Bright.

Annoying Dog

The Annoying Dog item has battle abbreviations for normal ("Annoy Dog") and serious ("Dog") mode programmed. However, the Annoying Dog can't be put in a Dimensional Box and will disappear if the player leaves the room it is found in, so it can never be brought into battle. As such, these strings can't be seen without editing the game.

Error messages

Snowed Inn error


A generic error message, found among the strings for Snowdin's Snowed Inn.

Undyne chase error

* A rousing error.
* (Error.)

Among the strings used when Undyne collapses from heat exhaustion are these two error messages that appear to serve the same purpose.



Among the strings used when Papyrus calls you about your clothing and Undyne's murderous intentions towards you is this error.

A trip to errorland

* Where will we go today?

         Error       Error

A developer's hell.

This is among the River Person's lines. Can be activated by talking to The River Person during the transition by using debug mode to move.

Alphys shipping error

* Error...

A generic error message located directly after Alphys asks the player if they think Toriel and Asgore will get back together. Guess not.

You've elected me in error

WOWi, Nice error.

Right after you're asked to be the ambassador to the humans is this error.

Flavor error

  Yes         No      

If you reset your game, Toriel will guess your favorite pie flavor from the choice you made pre-reset. If this went wrong, this would probably be displayed.

ACT menu error

    * Error

At the very end of the ACT menu strings is this yet again generic error message.

Item menu error

* If you are reading this,&  I messed up somehow./%

The message that shows if you try to get info for a slot that's empty in your inventory.

Item description error

* Error!

This same generic message appears again at the end of the strings listing the item descriptions.

Papyrus call error


Among Papyrus's lines for when he talks about the spaghetti trap room with what he says depending upon if you say you ate it or left it is this error. This probably would have appeared if your choice could not be determined by the game.

Undyne call error

* Error?

Among Undyne's lines for when she talks about Monster Kid depending on whether you saved them, ran away and had Undyne save them, or otherwise ran away is this error. This probably would have appeared if your choice could not be determined by the game.

Ending call error

 [look left]  * i'll be honest.
  [winking]   * i have no idea what
                happened for you
                to get here.
 [look left]  * this is actually some
                sort of error-
                handling message.
[eyes closed] * so, if you're getting
                this ending...
 [look left]  * tell whoever made the
                game, okay?
  [winking]   * they'll fix it, or
                if it's a novel
 [look left]  * they might even add
                another ending to
                the game.
[eyes closed] * chances are, though...
  [no eyes]   * you're just a dirty
                hacker, aren't you?
 [look left]  * yeah, get outta here.

Dialogue spoken by the character Sans for an ending meant to function as an error handler if none of the qualifications for any other endings are met, which cannot be triggered during normal gameplay. The actual script data contains control codes to change Sans's expression, represented here by bracketed text.

The music track "Dogsong" is played while Sans is speaking.

(Source: YouTube: Undertale "dirty hacker" ending)

Gyftrot error


This generic error that you've seen a million times appears again among Gyftrot's strings.

To do:
I got lazy after this, I'll describe the errors better later, and probably put all of these unused strings into subpages when I can.

Aaron error ;)

; )

Flagrant error message found in Aaron's strings ; )

Mettaton quiz show errors


A second error can be found if no question is available, yet the game still attempts to load one anyway:

No question.

The following answers, in order 1-4:

Happy Beefsteak
Thunder muffin

There is no correct answer. (Listed as -1)

Errror Babye

This misspelled (probably on purpose) error is shown when you get a question right, yet an error occurs.

8-legged error, ahuhuhu~

... that this is&an error message!?

Finally, a slightly interesting error message!

This appears after Muffet receives a telegram from the other spiders that changes depending on your spending choices.

Papyrus fight error


Flowey's Error

* Error

Flowey will display this message and soft-lock the game if you manage to get in his room before fighting Toriel.

Papyrus's puzzle error

Error, Pepibs.

Grievous error

* grievous error

Placed among the strings for the annoying dog absorbing the artifact and Sans's asking to hang out.

Mettaton fight error

* Error Baby

That error's a bomb!

* Error.
* Error,

These two generic errors are among the lines for the bomb-defusing minigame.

Burgerpants error

* I'm a goofy goober Yeah 
  this errorr. message.

The strangest error message so far is among Burgerpants's lines. It appears to be a reference to the 2004 film The SpongeBob SquarePants Movie.

Newspaper writer error

* Beautiful.
* An error message.

True Lab error


Piano Error

"* Come on! What are you doing!/%%"

Found among code for the Piano that appears in Waterfall. Though nothing calls the alarm where this text is, leaving it impossible to appear in normal gameplay. (gml_Object_obj_piano_Alarm_0)

Mad Dummy Error

* This message will NEVER& happen.

Mixed in with Mad Dummy's flavor text. If something went wrong during the fight, this would probably be displayed.

Moldbygg Error

* Wrong message!/^

Yet another generic error message, but this time it's Moldbygg flavored. Yay.

Astigmatism Error

* You execute some action./^

Error message related to ACTing in the Astigmatism fight.

Papyrus Date Error


Very blunt message if inspecting Papyrus' hat during his date doesn't work properly.

Papyrus's toolshed


If you get into Papyrus's toolshed by manipulating save data, reading the note will result in this message.

Legendary Artifact

* (This will never happen.)

Normally, attempting to obtain the Legendary Artifact will cause a dog to appear in your inventory, which will then steal the Artifact when used or dropped. However, if you remove the dog from your inventory via debug mode or other means and interact with the Artifact again, you'll get the placeholder dialogue above and the artifact will disappear.

Inaccessible Echo Flowers

* Error!

Interacting with any of the numerous inaccessible Echo Flowers in Waterfall will give this generic error message.

Unused pre-battle messages

You shouldn't read this.

The battle encounter that involves Aaron and Woshua being freaked out by Napstablook's music is not supposed to show a "pre-battle" message.

* Prove to me that you&  are.../"
\E1* Hey^1, let me finish%%"

Found among the lines before the fight with Toriel. These cannot be displayed in-game, as the code that calls them (Seen below) requires that the kills in the Ruins and Snowdin to be greater than 11. As normally one can't access Snowdin without fighting Toriel, these lines go unused. Via Save editing or using Debug mode, one can see how they were meant to go. Should be noted that before those lines appear, Toriel's normal dialogue plays up until after her saying "Prove yourself..." then the lines will display. It is interesting that these lines do appear in the demo, but not the full game.

 if ((global.flag[202] > 11) && (global.flag[203] > 11))
            global.msg[5] = scr_gettext("obj_torieltrigger12_346") // obj_torieltrigger12_346 = "* Prove to me that you&  are.../"
            global.msg[6] = scr_gettext("obj_torieltrigger12_347") // obj_torieltrigger12_347 = "\\E1* Hey^1, let me finish%%"


Monster seems satisfied.

Unknown. Will appear by pressing O + P in debug mode while fighting Mettaton EX, then sparing him.

Quiche Guilt

* Somewhere^1, a quiche's worst&  fear becomes reality./%%
* A quiche in another timeline./%%

Part of an unused set of scripts named "quicheguilt" that involves you standing still in the quiche room.

Horse Stable

Among the lines for the garbage dump and Napstablook's house, there are a few lines implying there was a horse stable somewhere in Waterfall.

* (It's a horse stable.)/
* (Do you want to go&  inside?)&         Yes         No \C
* (You jostle the door.)&* (It's locked.)/
* (Suddenly^1, from inside&  the [redacted], you hear a&/%%

Interestingly, we're hearing a noise from inside what is supposedly the horse stable, but for some reason, whatever it was is replaced with "[redacted]", and whatever it is that we hear at the end is just outright removed.

This dialogue seems to be triggered by a trash can in Napstablook's courtyard. Inspecting it if flag 92 (yet again unused) is less than 3 will cause the same figure from room 272 to appear inside the "stable", and say

* x/%%

in Wingdings.

Monster History Part 6

Unused monster history text that is the only outright confirmation of what "fallen down" monsters as discussed in Alphys's journals are.

(It's a book labelled Monster History Part 6.) Read it Do not
Unfortunately, monsters are not experienced with illness.
However, when monsters are about to expire of age, they lie down, immobile.
We call this state "Fallen Down."
A person who has Fallen Down will soon perish.

Mortal Enemy request

As this comes right after Napstablook's friend request in Hotland, it may have happened as a result of rejecting the request. In the final game, the friend request rejects itself regardless of your choice.

METTATON has sent you a Mortal Enemy request.
Congratulations! You are now Mortal Enemies with Mettaton.
COOLSKELETON95 has posted a comment on this change.
You rejected the request.
METTATON has sent you an invitation to "Die."
RSVP? Respond Ignore

Art Club Room

(Art club is cancelled!)

This message can be found if you read the sign in the art club room in Hotland (where the secret boss So Sorry normally is) on a genocide route. However, the entire second floor of Hotland is blocked off by a force field on a genocide route, making this impossible to see normally. As the sign suggests, So Sorry never appears there during a genocide route.

Slow-dance with Mettaton

Among the lines for Undertale the Musical are these lines (gml_Object_obj_playmovement_Step_0), possibly indicating you were originally meant to dance with Mettaton:

(Hmmm? Getting creative?)
(Dance with me, darling.)
(Oh! The audience can feel#your passion!)
(Show the audience#your passion!)
(So close... How passionate...)
(... do you need some help?)
(... what ARE you doing?)
(Don't stop now!)
(Look at you, leaping around#the stage...)
(Can't keep your hands off, huh?)
(Is that how humans dance?)
(Humans are stranger#than I thought.)
(Oh! They're really#getting into it.)
(Moving so far...)
(Who can blame you?)
(Hmmm, I'll have to get used#to it...)
(Even better than#I thought...)
(So that's wha #it's like.)
(Dancing with... A human.)
(What a shame...)

These can be seen in the Xbox One release as intended.


"obj_testmonster" is an enemy called "TestMonster", an early version of Froggit which, despite appearing to be a simple dummied-out enemy, is actually a cleverly-hidden event trigger that, if encountered in Sans's room after befriending Muffet on your 255th playthrough or later, proves key to reviving Gaster and saving Asriel. Just kidding, it was used for testing.

It shares many of its battle dialogues with Froggit, but it has a number of extra lines buried in its code.

* You feel intimidated by the&strength of this adversary.^4 &* Just kidding.
* The enemy cooks a small&bowl of flies.
* You can't concentrate&over the sound of croaking.
* The battlefield is filled with the smell of mustard seed.
* You think hard about words&that rhyme with frog.^4 &* Log.^4 Dog.^4 Snog.^4 Pog?
* A frog can't lick its&wounds because its tongue is&just too stretchy.
* You say some raunchy&things to those frogs.&Jeeeez!/
* There's definitely some&sort of reaction./^
* What's your favorite color?& &    * Red           * Orange"
* Do robots dream of&electric sex?/^
* I hate programming this./^

Flowey's big boner

* Big boner down the lane^8 %%
* Big boner down the lane^4 %%

These two strings are located among the dialogue for the Photoshop Flowey boss fight and the hacked "Floweytale" intro sequence. It's unsure what they could have been used for, but they likely were never meant to be seen by the player.

True Lab Entry Number 17

monsters' physical forms can't handle "determination" like humans' can.
with too much determination, our bodies begin to break down.
everyone's melted together...

Alphys' entry number 17 is skipped in the True Lab, but is found in the code. Alphys instead explains this at the end of the area. W.D. Gaster has his own entry 17, which can be seen in room_gaster.

Various Bepis Messages

Papyrus Never Bepises


Located amongst various Papyrus strings in the latter half of Snowdin.

Bepis Clothing


Placeholder for Papyrus’ dialogue when he calls to ask what you’re wearing, and when he calls to tell you what he told Undyne, if he can't tell what armor you're wearing for some reason. This can actually be seen if you hack the game to give yourself armor that isn't accessible at that point.

Glyde's Rad Bepis


Generic Bepis located within Glyde's battle strings.

Bepis valley Granola Bars

Bepis valley Granola Bars

Found along the lines of the unused "Mortal Enemy request" text. Yes, a placeholder for unused text.



A variation on Bepis! Located amongst the strings for Sans' judgements.

Asriel Bepis

Ultimate bepis/%%

The culmination of Bepis. Located within the strings related to Asriel's final form.

Papyrus and The Locket


Text for The Locket during Papyrus' date that isn't seen, because you can't obtain it on a non-Genocide run.

Doge Fight

Come on,&let's go.
Want to&go on&a walk?
Oh boy!&Oh boy!&Oh boy!&Oh boy!
* Doge is pacing anxiously.
* Doge paws at an imaginary& door.
* Doge is looking at you and& whining.
* Doge is wondering where she& put her leash.
* Doge is now primed for petting.
* Doge looks satisfied.
* Doge needs a vet.
* DOGE - ATK 7 DEF 5&* Pronounced "dohj." Soft j^1.&* Seems like she wants a walk./^
* You tried to bathe Doge^2,& but she's perfectly clean.../^
* You go on a short walk with& the Doge./^
* The Doge seems all tuckered& out./^
* You called Doge over.&* Doge came close./^
* Dry a dry doge?&* Your mind boggles at this& impossibility./^
* You pet the Doge.&* What a good Doge./^
* Doge seems too dangerous& to pet..^1.&* For now./^

All of these were meant for an unused fight against an enemy named Doge. Unlike RG 03 and RG 04, this fight was never programmed in, however it got far along enough to get strings written in and an unused sprite.

Undyne's Hamburger Helper

* Hamburger Helpers./^

Odd text for Undyne's regular fight. Most likely just a placeholder.

Mettaton Rules The School

* MEttaton Rules the school.
* Mettaton is A- OK .

Very odd placeholder dialogue for the pre-EX fight.

Instructions Room

Game Under
Big Wienener Zone.
Hall of failure.
TAke a screenshot#of this every time#for balancing purposes.
Hold SPACEBAR to restart from#Attack 30
waiting for the#next battle...
attack Number
final attack
heal items left
press H to use one
your HP is
press SPACE to continue
blue lasers don't hit#you if you don't#move

Seems to be leftovers from a room made for testers to test out the battle system, specifically Mettaton's shooting segments and blue attacks.

Capital Wenisberry

* Capital wenisberry./%%

Most likely a placeholder, located right before the Cooking With a Killer Robot segment.

Toby's Frustration

What the fuck is wrong

Located right after the Undertale the Musical segment. Seems like developing this part was difficult.


* East: Burgertown&* North: Cord&* West: Restraint/ ~
* This area's not done so no& fun is allowed here yet./
* Signed, the Manmengent/%%

Very odd strings. May have been jokes purely for testers to catch while testing out the hotel, considering the names of the locations listed being slightly off to what surrounds the hotel, and where the strings themselves are located.


\Ts %

Purpose unknown.

Numbered Tests

* Test one./
\E1* Test two./
\E2* Test three./
\E3* Test four./%%


Impatient Test

* This is a damned test!/

Okay, jeez, it's a test!

Triggered Undyne Test


Found in gml_Object_obj_undynetrigger_boss_KeyPress_32 is a generic test message.

Unusual String

* 0^1. \E1 1^1. \E1 1^1.\E2 1^1.\E3 1^1.\E4 1^1.\E5 1^1.\E6 1^1. \E7 1^1.\E8 1^1./%%

Your guess is as good as mine.

Last Chance to Wish

* (Last chance to wish& before Hotland^1.)&* (Careful of pollen.)/%%

Seems like this would've been used in relation to the last Echo Flower room in Waterfall.


G - Ninechara
(9999 G)
Really sell Ninechara for

Seems to be leftovers from a placeholder item, in relation to the nine character limit for items in general.

Mettaton in Snowdin


Unused Mettaton dialogue... However, it’s located within the dialogue for Snowdin’s residents, for some reason. Perhaps you could talk to Mettaton in the Snowdin tile puzzle room? Has been removed as of version 1.08.

Bridge Seed Failure

* (You hear a small voice.)/
* Congratulations!/
* What's wrong with you!/%%

Found within gml_Object_obj_waterboardpuzzle1_Step_0. If Won = 98, snd_dumbvictory would play and this text would get displayed. This is, of course, impossible in the final game, as there's nothing you can do in the room that would activate this.

Dog Error Screens

Two screens featuring the annoying dog are present in the game. These are used as "error handlers" in case something goes wrong, such as loading a corrupted save file or entering an invalid or otherwise inaccessible room.

The song "mus_dance_of_dog" is used on one of the error handler screens (the left one), at a random pitch. The other song is "mus_sigh_of_dog".

Unused Items

ID Name Short Name Serious Name Description Use Text
2 Croquet Roll CroqtRoll CroqtRoll Heals 15 HP

Fried dough traditionally served with a mallet.

You hit the Croquet Roll into your mouth.
5 Rock Candy RockCandy RockCandy Heals 1 HP

Here is a recipe to make this at home:

1. Find a rock

You ate the Rock Candy.
6 Pumpkin Rings PunkRings PmknRings Heals 8 HP

A small pumpkin cooked like onion rings.

You ate the Pumpkin Rings.
8 Stoic Onion StocOnion Onion Heals 5 HP

Even eating it raw, the tears just won't come.

You ate the Stoic Onion. You didn't cry...
9 Ghost Fruit GhostFrut GhstFruit Heals 16 HP

If eaten, it will never pass to the other side.

You ate the Ghost Fruit.
18 Puppydough Icecream PDIceCram Ice Cream "Puppydough Icecream"

Heals 28 HP. Made by young pups.

Note: This item's name is too long to show up properly when using a dimensional box.

Mmm! Tastes like puppies.

(Source: rawr.ws)

Unused Item Drop

In the code for Monster Setup (gml_Script_scr_monstersetup) there is mentions of item reward ids and the chance for the item to drop. Though this never happens within the game. Leaving these variables unused; itemrewardid and itemrewardchance. Below is an example of the variables in the code.

    global.monstername[myself] = scr_gettext("monstername_3") // monstername_3 = "Froggit"
    global.monstermaxhp[myself] = 20
    global.monsterhp[myself] = 20
    global.monsteratk[myself] = 4
    global.monsterdef[myself] = 1
    global.xpreward[myself] = 10
    global.goldreward[myself] = 20
    global.itemrewardid = 1
    global.itemrewardchance = 50


Annoying Dog's Sale Price

The Annoying Dog can be sold for 999G and haggled up to 1251G (the highest sale price of any item in the game!), but as mentioned above, it will disappear if taken out of the room it spawns in, so this can never be seen on a normal playthrough.

Mettaton's House

Mettaton's bed, upper walls, and TV have collision, but it's impossible to get in that section of the room.

Developer Oversights

Mettaton EX Battle Essay

Mettaton EX has an "essay" question where you can type in text and have him comment on it. Unfortunately, typing "x" or "z" ends the essay unless CTRL is held down, leaving some words (in most playthroughs) untypable. This was corrected in the PlayStation 4, PlayStation Vita, and Nintendo Switch versions of the game, as they use an on-screen keyboard.

The following words can't be triggered:

  • sexy
  • foxy
  • tantaliz (covers both "tantalizing" and "tantalize")

Naming the fallen Human

In the PlayStation 4 and PlayStation Vita versions of the game, entering the name "Gaster" will result in a crash, rather than the intended reset.

(Source: Twitter)

Version Differences

To do:
  • Add the updates from the Nintendo Switch editon, and the other updates released on console only. Use this, if needed.
  • It seems that Toby silently patch the game with the PS4 feature (The Dog Shrine) being added, although inaccessible. The latest version is currently at v1.06. Find the rest of the changes on previous versions, as well as adding this to access the shrine in the PC version.
Windows/PS4/Vita/Switch OS X/Linux
Undertale-LabWindows.png Undertale-LabOSX.png

In the Windows and console versions, the monitor in Alphys's lab follows your movements. However, this is only a static image in the OS X and Linux versions. The static image for the monitor is still in the Windows version's files, unused.


Undertale Lab monitor sprite rip 1.png


Undertale Lab monitor sprite rip 2.png

1.001 patch

To do:
Hastily pulled from the Undertale wiki. Add anything that's somehow not on that page, and add detail to this stuff.
  • The loading splash screen from the demo was restored.
  • The Joystick Config menu was graphically updated.
  • A kill sprite was added for "Ice", which is encountered by stealing Ice Cap's hat. Previously, it mistakenly used a placeholder sprite of Aaron.
v1.0 v1.001
UNDERTALE-BlueAttack-Old.png UNDERTALE-BlueAttack-New.png
  • The color of blue attacks was adjusted somewhat for the benefit of colorblind players, as the original, cyanish hue made them almost identical to (for protanopia) or only slightly darker than (for deuteranopia) white attacks.
  • Some dialogue was updated to account for aborted genocide runs, such as the phone call in the invisible maze room, Papyrus's bone box during his date/hangout, and possibly more.
v1.0 v1.001
UNDERTALE-UndyneCutscene-Old.png UNDERTALE-UndyneCutscene-New.png
  • An oversight that would cause Papyrus to appear during the cutscene where Undyne first appears, even on routes where he was killed, was fixed.

  • A visual solution was added to the piano puzzle for the benefit of hearing-impaired, tone-deaf, or just plain uncertain players.
  • Dialogue relating to the "Clam Girl" NPC in Waterfall was changed and added.
  • The grandpasemi.ogg sound effect was renamed to grandpatemi and repurposed for Temmie, if you refuse to give her Tem Flakes.
  • Various layout changes were made to attempt breaking the "Lab Skip" glitch. This didn't quite work.
v1.0 v1.001
UNDERTALE-AlphysLabBathroomSign-Old.png UNDERTALE-AlphysLabBathroomSign-New.png
  • The bathroom sign in Alphys' Lab was moved from the right side of the door to the left side in order to patch the bug described above.
  • New dialogue was added for Burgerpants involving the Nice Cream Man.
  • The advancement of Sans's pre-fight text was altered slightly. He now says the short version after you survive the opening attack three times, rather than after he is defeated once and the player reloads to fight him again.
(Upon closer examination, the holes in the fabric seem to be growing.)
(Might take a while for the dog to fix all of them.)
(Dogs aren't usually very good at knitting.)
(A crocheting dog is out of the question.)
  • Dialogue was added to the secret Annoying Dog room, elaborating further on the "patch" that is supposedly needed before the Dog can be fought.
  • As detailed above, the "don't spoil the game, dataminers" warnings were changed due to no longer being necessary.
  • The Gaster-related "fun" setting now works without having to manually edit the .ini file first.
  • The Check option in battle no longer shows the actual stats used by the game code, instead displaying arbitrary numbers or silly messages.
  • The original version of the game had a major oversight that would allow the player to achieve a True Pacifist ending while having a non-zero amount of EXP (by reloading after a Neutral route in which no monsters were slain, killing some monsters in the Core, and then going to pick up Undyne's letter).
  • The unusually large space between Asgore and Monster Kid on the final version of the menu screen was shortened.
  • A (presumably) debug feature that would cause Undyne and Alphys's kissing animation in the cutscene leading up to the Asriel fight to start early by pressing the space bar was removed.
  • Various graphical glitches and typos were fixed.

A "1.001v1" patch was later released. This is a Steam compatibility update. Only one thing has changed; entering "Gaster" as the fallen human's name will reset the game, just after typing it. In the previous version, it only does so if you confirm the name.

Linux patch

The Linux version of the game is identical to 1.001, but includes a bugfix where pressing Z while pressing Enter would not register the Z input.

Console Versions

The PS4 version added trophies.

Full-Screen Froggit

In the Ruins, the Froggit that mentioned pressing "F4" to enter full-screen was replaced by a Froggit that mentions that the border can be changed in the settings menu on the main menu.

Tiny Ruins Froggit

PC Console
* (There's an ant-sized frog in a crack in the wall...)
* (It waves at you.)
* (There's a small crack in the wall here.)
* (There's a frog inside...)
* (Wait! There are two!)
* (You had a wonderful, exclusive experience...)
* (... that only someone who saw two frogs could feel.)

As a result of removing the mention of "four frogs in this room" by the previous Froggit, this dialogue was changed.


The ITEMS option appears grayed out on the menu if you do not have any items.

Papyrus's Sink

To do:
Images that aren't from video footage, along with Mad Mew Mew and Slot Machine music.

In the console versions of Undertale, a new area exists underneath Papyrus's sink.

PS4 and Vita

In the PS4 and Vita versions, this area is the Dog Shrine, which is both a reference to a box full of goodies that Toby Fox was given at a Japanese Undertale event (thereby explaining the Japanese theme), and most likely a parody of the Kickstarter campaign. You can donate gold to it to have it decorated with various items. The price gradually increases every time you donate, however. Each time you donate, you get a PlayStation Trophy. This area has two new music tracks, the second being unlocked after donating six times:

A remix of the song that plays in the Annoying Dog's room, played with traditional Japanese instruments...

...and a (somehow) even goofier version of Dogsong, played with instruments from Super Mario World.

If Papyrus isn't befriended, the donation box will appear in the trash area of Waterfall; however, donating here will only give you the trophies.

Nintendo Switch

In the Nintendo Switch version of the game, the Dog Shrine is still present, but has fallen into disrepair and no longer functions. Instead, this area is home to a bonus boss fight against the Mad Mew Mew (actually the Mad Dummy haunting a discarded Mew Mew Kissy Cutie doll, whose attacks must be avoided using the Joy-Cons), which is unlocked after encountering the Mad Dummy and returning to Snowdin. This battle uses a unique remix of "Ghost Fight". Successfully completing this boss battle replaces Mad Dummy in the True Pacifist credits with their new identity, Mew Mew.

Xbox One/Series X

In the Xbox version, both the Dog Shrine and the Mad Mew Mew fight are replaced with a slot machine. The player can exchange Gold for Dog Coins, which can then be used on the slot machine to multiply the current amount of Coins. Afterwards, the player can donate the Coins they have to receive prizes, which (like the PS4 and Vita version's Dog Shrine items) are simply static, interactable objects, along with achievements. Once all of the prizes are obtained, the player will instead get the equivalent amount of Gold for every donation they make.

Sans makes an appearance with the poker table prize (referencing an unused concept for the game, where Sans was originally going to run poker at a casino), and has several bits of dialogue that correspond with each prize. After beating Mettaton, like the Switch version, Mew Mew appears in place of Sans. Along with this, she also has different dialogue. A new music track accompanies this room.

If the controller happens to disconnect during gameplay, you will receive a message informing you of this, as well as some story/room dependent text.


In all of the console versions, the player can select a border to surround the game screen during play. At the beginning, the player can only select "Simple", "Sepia", and a "Dynamic" border that changes to match each area the player passes through, with the respective designs being unlocked after achieving an ending. A "Beauty" border is unlocked after beating the hidden Hard Mode.

The Nintendo Switch version adds two more unlockable borders. One of them is a Mew Mew Kissy Cutie-themed border unlocked after fighting Mad Mew Mew, and its title will be "Real" or "Not Real" depending on the player's answer when Undyne asks if anime is real. The other border is a dog-themed border titled "Super Dog, Hoi", which is unlocked by deploying the Annoying Dog in the Artifact Room.

The Xbox version comes with another unlockable border. After visiting the slot machine room, a casino themed border is unlocked. Interestingly, this border features cameos from Deltarune characters, such as Jevil, Lancer and C. Round.


In the PS4 version, your HP is displayed in pink the entire fight, regardless of whether or not you are taking KARMA damage. This visual quirk isn't present in the Switch version.


In the Japanese version of the game, Papyrus's dialogue is uniquely written in the traditional Japanese style (top-to-bottom, right-to-left).

So Sorry

Normally, the bonus boss fight against So Sorry in the Hotland Art Club requires the player to enter the room on October 10th at 8:00pm. In the Nintendo Switch version, the player can fight So Sorry at any time during October 10th. The sign hasn't been changed to accommodate this, though. Additionally, Samael (So Sorry's creator) is now credited.

(Source: Toby Fox on Twitter)

Clam Girl

The Clam Girl, one of the possible NPCs who can appear under specific "Fun" values, has received a change in the Nintendo Switch version. When spoken to during the True Pacifist epilogue, she will tell the player that they haven't met Suzy yet, and that the time they will meet is fast approaching. As she almost finishes her dialogue, her face changes and greys out, then mysteriously vanishes in a similar fashion to the Mystery Man and one of the Gaster followers. This may be a tease for the game Deltarune, as a character in that game is named Susie (with different spelling, however).