Inaccessible rooms

In Undertale's files, the player cannot access some rooms by conventional means. If the player attempts to access these inaccessible rooms (the "Dogcheck" rooms are 0–3, 78–80, 239–241, and 266–335), the "Dogcheck" value returns out of range and causes the Annoying Dog to appear in the middle of a black screen while either mus_sigh_of_dog or Dance of Dog plays, with a few rare exceptions.

The rooms below are listed in numerical order. Note that all rooms on the Xbox versions are offset by 1, so the Xbox room number is always the next room number up compared to other versions.

room_water_prebird

Layout of room_water_prebird

room_water_prebird is room 123 in most versions and room 124 in the Xbox version. It is located between room_water_farm and room_water_shop. Its internal label suggests that Toby Fox may have planned to place it before the small bird that carries the protagonist over a disproportionately small gap. The room has a thin stretch of land surrounded by water on two sides. Grass covers the path, and the protagonist can interacts with two NPCs hidden within it. One NPC remarks that they love to catch bugs in their spare time, and the other one asks the protagonist to do something about their friend, who the NPC notes has a creepy smile. If the protagonist speaks to the second NPC again, the NPC asks where their friend went. Exiting the area on the left crashes the game, and exiting to the right softlocks the game at a black screen. Unlike most of the other rooms stated here, it is not Dogchecked.

Dialogue

[At the left end of the tall grass]

• (Whenever the girl moves her net, this bug scurries straight into it.)
• Excuse me... Yes, you, with the striped shirt.
• Can you do something about your friend...?
• Yes, your friend... The one behind you, with the creepy smile.
• Hmmm? Where'd your friend go?

[At the right end of the tall grass]

• I'm catching bugs. But the underground doesn't have many...
• I keep catching the same one.
• Achoo! Tried to catch a bug, but I just caught a cold...

room_gaster

ENTRY NUMBER SEVENTEEN in room_gaster

room_gaster is room 264 in most versions and room 265 in the Xbox version. It is black and displays shaking, white text in a pixelated Wingdings font. A glitchy, robotic sound internally referred to as mus_smile plays in the background. The text's voicebyte consists of snippets of abc_123_a. Once the message ends, the screen turns black for a moment before the game closes. Unlike most of the other rooms stated here, it is not Dogchecked.

ENTRY NUMBER SEVENTEEN

• ENTRY NUMBER SEVENTEEN
• DARK DARKER YET DARKER
• THE DARKNESS KEEPS GROWING
• THE SHADOWS CUTTING DEEPER
• PHOTON READINGS NEGATIVE
• THIS NEXT EXPERIMENT
• SEEMS
• VERY
• VERY
• INTERESTING
• ...
• WHAT DO YOU TWO THINK

room2

room2 is room 267 in most versions and room 268 in the Xbox version. It displays three Froggit sprites before printing the screen red and loudly playing the enemy defeated sound. After a while, the game crashes.

This room is present in the Undertale Demo as room 2, which explains why its internal name is room2 in the final game.

TESTROOM

Animation of monsters speaking in TESTROOM

TESTROOM is room 271 in most versions and room 272 in the Xbox version. It is gray and has three text bubbles next to one another. Text within the dialogue boxes sways. "TestMonster and its cohorts draw near!" is displayed vertically beneath the second dialogue box, likely in reference to Earthbound, in which multi-enemy encounters often begin with the text "[Enemy] and its cohorts draw near!".

This room is present in the Undertale Demo as room 0.

Dialogue

• La, la. Time to wake up and smell the pain.
• Though.... It's still a little shaky.
• fhuehfuehfuehfuheufhe

(Vertical text - goes offscreen)

• TestMonster and its cohorts draw near!

No more text prints after the last dialogue.

room_water_redacted

room_water_redacted, with spr_redacted_a

room_water_redacted is room 272 in most versions and room 273 in the Xbox version. It is black and has an NPC internally referred to as spr_redacted_a in the middle. As the protagonist approaches, the NPC fades and, when spoken to, says "[redacted]" in Wingdings. Premonition plays when the NPC begins fading in (which is the instant the player spawns, unless modified). If the protagonist leaves through the south exit, they enter the Sound Test room.

room_water13

Layout of room_water13

room_water13 is room 273 in most versions and room 274 in the Xbox version. It uses assets of the Waterfall area and features a long narrow pathway that leads to a large area of land covered in tall grass. The protagonist can find Bridge Seeds in the grass and can use these seeds to reach a pathway on the right side of the room. The large grass field has a Bridge Seed that, according to the code, would run away from the protagonist until they catch it. It is named obj_runaway internally. The exit here leads to room_overworld. Walking to the bottom crashes the game.

This room used to connect room_water12 and room_water14 before Onionsan was implemented.

room_overworld

Layout of room_overworld

room_overworld is room 274 in most versions and room 275 in the Xbox version. It is black and features 3 pillar-type characters with stoic faces, similar to the protagonist's expression, while Determination plays. In the game files, these sprites are simply named spr_test. Talking to these NPCs crashes the game, as it attempts to access a seemingly missing file named testlines.txt. But if the file named testlines.txt is created in the game directory, it instead displays the text from that file. The protagonist can activate Flowey's initial encounter trigger, which normally initiates a (glitched) battle with Flowey; however, if Flowey was killed in a previous Neutral Route, it skips to Toriel's subsequent dialogue.

This room is present in the Undertale Demo as room 5.

room_overworld3

room_overworld3 is room 275 in most versions and room 276 in the Xbox version. It is mostly a black room. It has only a door back to room_overworld.

bullettest

Bullet testing in the bullettest room

bullettest is room 276 in most versions and room 277 in the Xbox version. It is a variant of the first Froggit encounter with Toriel. If the Froggit is not killed immediately, Toriel appears and scares the Froggit away. The game then returns to the previous room (if the SAVE file is edited then launched, it restarts due to the lack of a previous room). The edges of the bullet box are missing with the SOUL stuck at the center of the screen with text saying "Froggit attacks you!" laid over it and red, triangular rays appear out of the SOUL, then sweep to the right side of the screen and turn green. The buttons usually at the bottom of the screen are replaced with rows of Omega Flowey's friendliness pellets coming out of the bottom of the screen and curving away from the SOUL.

room_water16A

room_water16A is room 277 in most versions and room 278 in the Xbox version. It seems to be a black room. It may have been a room for the Waterfall area.

room_spritecheck

room_spritecheck is room 287 in most versions and room 288 in the Xbox version. It is gray and displays every single sprite in a rapid succession. After Undyne the Undying's head loads, the center-most sprite becomes a static sprite, though the others still cycle. There is also a 0 on the screen, and after all the sprites load, the 0 counts up. Pressing the space button in this room brings up the Joystick Config room.

room_fire4

Layout of room_fire4

room_fire4 is room 296 in most versions and room 297 in the Xbox version. It uses assets of the Hotland area and the mysterious door's dog room floor. It features a path lined by steam vents that goes up and then turns right. The protagonist can access said vents by walking through the wall. Another Medium, a reoccurring song in Hotland, plays in this room. Going below sometimes loads room_floweyx (room 294 in most versions and room 295 in the Xbox version), the room containing Omega Flowey's battle, which crashes the game. Going right also crashes the game.

Sometimes, a dialogue box displays the Undertale prologue.

room_fire10_old

Layout of room_fire10_old

room_fire10_old is room 297 in most versions and room 298 in the Xbox version. It uses assets of the Hotland area, and conveyor belts line a pathway that the protagonist must cross to get to the other side. If the protagonist falls off a conveyor belt, they find themself in room_fire10A_old. The exits on the right and left of the room are nonfunctional.

room_fire10A_old

Layout of room_fire10A_old

room_fire10A_old is room 298 in most versions and room 299 in the Xbox version. It uses assets of the Hotland area and contains two platforms, one at each end of the room, that are linked by conveyor belts. A single Echo Flower located in the middle of the room says "Error!" The right side of the room has a door that leads to room_fire10_old, and the other end of the room has a bowl of dog food. The protagonist can find the same bowl in Papyrus's toolshed.

room_tundra_placeholder

Layout of room_tundra_placeholder

room_tundra_placeholder is room 299 in most versions and room 300 in the Xbox version. It uses assets of the Snowdin area and consists of an ice puzzle. If the protagonist attempts to solve the puzzle, the ice pushes the protagonist backward when touched. There is nothing located at the end of the puzzle, and this room does not connect to any other room.

room_ruins12B_old

Layout of room_ruins12B_old with the Rock Candy

room_ruins12B_old is room 300 in most versions and room 301 in the Xbox version. It uses assets of the Ruins area and is similar to room_ruins7A, the room where the protagonist can find Monster Candy. Instead of Monster Candy, this room has Rock Candy, and the protagonist can only hold one Rock Candy at a time; to take another, the protagonist needs to eat or drop the piece of Rock Candy that they currently have.

room_tundra_rollsnow

Layout of room_tundra_rollsnow

room_tundra_rollsnow is room 301 in most versions and room 302 in the Xbox version. It features a small snowball whose mechanics are similar to the Ball Game in Snowdin. If the protagonist pushes the snowball, it gradually grows until it reaches maximum size. This room does not connect to any other rooms.

room_water7_older

Layout of room_water7_older

room_water7_older is room 302 in most versions and room 303 in the Xbox version. It is an old version of the room before the second Undyne encounter, and the game crashes when the room is loaded unless the file "obj_waterpushrockgen" is edited or deleted. This room has a single Echo Flower that was supposed to say "Sitting behind rushing water... It makes me feel relaxed." and several torch-like objects that may be placeholders due to their poor quality. The tops of these objects ignite when the protagonist interacts with them. This room may be an unfinished puzzle similar to the torch puzzles in The Legend of Zelda. Leaving this room crashes the game.

room_meetundyne_old

Layout of room_meetundyne_old

room_meetundyne_old is room 303 in most versions and room 304 in the Xbox version. It is an old version of the room where the protagonist initially meets Undyne. There are some NPCs and a sign that functions as an Echo Flower; it reiterates the last line of dialogue that the protagonist heard from the NPCs, likely due to the sign not having dialogue. This room also has the final version of ths scene in which Undyne first appears (obj_undyne1). After Papyrus talks to Undyne, Monster Kid's dialogue displays even though they are not visible in the room. The right exit leads to room_water_mushroom. An early version of the scene exists (obj_undyne1_old), which doesn't have Papyrus and would involve Undyne slowly walking from the right and scaring the two NPCs, then turning back. After that, Monster Kid would appear, and their dialogue is the same as the final version.

Dialogue

[When interacting with rabbit-like NPC]

• We're about to visit Snowdin for the first time.
• You just came from there, right?
• How is it...?
• You should go back to Snowdin. [After Undyne's dialogue]

[When interacting with other NPC]

• Hey, I haven't seen you around before.
• It's nice to meet new people, isn't it?
• I... I don't know you. [After Undyne's dialogue]

room_water_mushroom

Layout of room_water_mushroom

room_water_mushroom is room 304 in most versions and room 305 in the Xbox version. It features an NPC that asks the protagonist what the "outside" is like. The NPC then asks the protagonist to investigate the room to the right (room_monsteralign_test) and return to tell him what they found. His dialogue is similar to Ragel's; he talks about being unable to explore because he is rooted to the ground. The NPC is unfinished as it uses the placeholder sprite of the ficus licker. The bottom exit connects to room_meetundyne_old, the right exit connects to room_monsteralign_test.

Dialogue

• It's a crystal. You've never seen one like this before. [Check crystal]

[When interacting with the NPC in the room]

• You... You came from outside, didn't you?
• People like you are so rare...
• Please! Stranger!
• Tell me about outside...?
• Is everyone out there like you? How terrible. [No]
• [Yes]
  • Huh? "SURFACE"? What do you mean?
  • I just meant outside this room.
  • If you haven't noticed, my mycelium have bound me to the ground.
  • Please! Stranger!
  • I'll make this simple.
  • I've spent my whole life in the same spot, in the same room.
  • But I've long wondered what lies inside the room to the right.
  • Long I've fantasized about entering, and changing my scenery...
  • No... Changing my LIFE!
  • Please. Go and tell me what's inside.
    • Well, what are you waiting for? [Talk again]
• [Intended for leaving and returning; unused]
  • Oh! You're back!
  • How's the room?
  • [Different]
    • Oh, that's a relief!
    • That's all I need to continue my fantasies. Thank you, stranger.
      • My mind is running wild! I haven't felt like this in a long time... [Talk again]
  • [Same]
    • So it's the same.
    • The same...
    • Same...
    • ...
    • OK.
      • Please leave. [Talk again]

room_monsteralign_test

room_monsteralign_test is room 305 in most versions and room 306 in the Xbox version. It is black and features a Memoryhead that disappears.

room_empty

room_empty is room 321 in most versions and room 322 in the Xbox version. It is a black room.

room_of_dog

Annoying Dog sleeping in room_of_dog

room_of_dog is room 326 in most versions and room 327 in the Xbox version. It is the Annoying Dog error room if the SAVE is invalid. The unlisted tracks Dance of Dog and mus_sigh_of_dog can play in this room.

room_quizholder

room_quizholder is room 327 in most versions and room 328 in the Xbox version. It is a black screen with Mettaton and Alphys, as seen in Mettaton's quiz show. Mettaton waves while Alphys looks on nervously. The player cannot do anything in this room.

room_friendtest

room_friendtest is room 328 in most versions and room 329 in the Xbox version. It is gray and was used to test the scene before the Asriel battle in the True Pacifist Route. It includes the final dialogues and battle sprites of all characters. Random sprites flash and scroll during the scene, including the sepia Asriel images Temmie Chang created. The game crashes after Flowey delivers the line "I'll keep you here no matter what!"

room_bringitinguys

room_bringitinguys is room 329 in most versions and room 330 in the Xbox version. It is black and was used to test the scene before Asriel's battle where the monsters encourage the protagonist to keep fighting. It includes the final dialogues and battle sprites of all monsters that enter during this scene; the main cast is absent. The game does not progress further than this scene. The name of this room is similar to the name of the Bring It In, Guys! track.

room_asrieltest

Placeholder SOUL sprite used in room_asrieltest

room_asrieltest is room 333 in most versions and room 334 in the Xbox version. It is black and was used to test Asriel's "God of Hyperdeath" animation. The SOUL is a placeholder sprite and there is no bullet board; the SOUL can move freely around and behind Asriel's battle sprite.

Asriel floats up and down as he does in-game, and he indefinitely shakes his head. After a few minutes, Asriel moves from side to side in an arc pattern as his rainbow sprites display.

Attempting to make Asriel attack via debug mode crashes the game.

room_afinaltest

room_afinaltest is room 334 in most versions and room 335 in the Xbox version. It was used to test Asriel's "Angel of Death" animation. The SOUL is the same placeholder sprite seen in room_asrieltest. The SOUL can move freely around the screen and is always in the foreground.

room_dogshrine

room_dogshrine is room 335 in most versions and room 336 in the Xbox version. It is a room introduced in the PlayStation version, where it is accessible in-game. This room is inaccessible in PC versions after v1.05 as well as the Nintendo Switch and Xbox versions. This room leads to the Dog Shrine.

This room did not exist on versions prior to v1.05.

room_dogshrine_ruined

room_dogshrine_ruined is room 336 in most versions and room 337 in the Xbox version. It is a room introduced in the Nintendo Switch version, where it is accessible in-game. This room is inaccessible in the Xbox version. It contains the ruined Dog Shrine from the Nintendo Switch version.

This room does not exist on the PC or PlayStation versions.

room_dogshrine_mewmew

room_dogshrine_mewmew is room 337 in most versions and room 338 in the Xbox version. It is a room introduced in the Nintendo Switch version, where it is accessible in-game. This room is inaccessible in the Xbox version. It contains the Mew Mew doll from the Nintendo Switch version.

This room does not exist on the PC or PlayStation versions.

room_of_bog

room_of_bog is room 338 in most versions and room 339 in the Xbox version. It is an unused room introduced in the Nintendo Switch version. This room is inaccessible in both the Nintendo Switch and Xbox versions. It is an empty black room.

This room did not exist on the PC or PlayStation versions.