Inaccessible Rooms

In Undertale's game files, the player cannot access some rooms by conventional means.List of rooms. Red text indicates Dogcheck check those rooms 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 cause the Annoying Dog to appear in the middle of a black screen while "Sigh of Dog" or "Dance of Dog" plays.
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 123 ==
 
Room 123, also known as room_water_prebird, is between room_water_farm and room_water_shop. Its name 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 talk to 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 says 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 264 ==
 
Room 264, otherwise known as room_gaster, is black and displays shaking, white text in a pixelated Wingdings font. A glitchy, robotic sound named mus_smile plays in the background, and when sped up is revealed to be Muffet's laugh reversed then played twice. The text plays random snippets of abc_123_a.ogg every time a character is typed out. 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 17 ===
* 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
== Room 267 ==
Room 267, also known as room2, displays three Froggit sprites before printing the screen red and loudly playing the enemy defeated sound. After a while, the game crashes.
== Room 271 ==
Room 271, also known as TESTROOM, 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, which is likely in reference to Earthbound, in which multi-enemy encounters often begin with the text "[Enemy] and its cohorts draw near!".
=== 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.
In the Undertale Demo, this room replaces room 326 if the SAVE is invalid.
== Room 272 ==
 
Room 272, also known as room_water_redacted, is black and has an NPC in the middle. As the protagonist approaches, the NPC fades and, when spoken to, says "[redacted]" in Wingdings. This NPC represents one of two possible sprites for W. D. Gaster. "Premonition" plays in this room. If the protagonist leaves through the south exit, they enter the Sound Test Room.
== Room 273 ==
 
Room 273, also known as room_water13, uses Waterfall sprites and has 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 exit here leads to room 274. Walking to the bottom crashes the game.
This room used to connect room_water12 and room_water14 before Onionsan was implemented.
== Room 274 ==
Room 274, also known as room_overworld, is black with 3 pillar-type characters with stoic faces, similar to the protagonist's expression, while Determination is playing. 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: this normally initiates a (glitched) battle with Flowey, but if Flowey was killed in a previous Neutral Route it skips to Toriel's following dialogue.
== Room 275 ==
Room 275, also known as room_overworld3, is mostly a black room. It has only a door back to Room 274.
== Room 276 ==
Room 276, also known as bullettest, 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 (however, if the SAVE file is edited then launched, there is no previous room, so it restarts). 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 Photoshop Flowey's friendliness pellets coming out of the bottom of the screen and curving away from the SOUL.
== Room 277 ==
Room 277, also known as room_water16A, seems to be a black room. It was probably going to be a room for the Waterfall area.
== Room 287 ==
Room 287, also known as room_spritecheck, 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 296 ==
 
Room 296, also known as room_fire4, uses Hotland sprites and Developer Room floor sprites. It has a path that goes up and then turns right, and steam vents line the path. The protagonist can access these vents by walking through the wall. "Another Medium," a reoccurring song in Hotland, plays in this room. Going below sometimes loads room 294 (Photoshop Flowey's battle), which crashes the game. Going right also crashes the game.
Sometimes, a dialogue box displays the Undertale prologue.
== Room 297 ==
 
Room 297, also known as room_fire10_old, uses Hotland sprites, 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 298. The exits on the right and left of the room are nonfunctional.
== Room 298 ==
 
Room 298, also known as room_fire10A_old, uses Hotland sprites and contains two platforms, one at each end of the room, that conveyor belts link. A single Echo Flower located in the middle of the room says "Error!" The left side of the room has a door that leads to room 297, 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 299 ==
 
Room 299, also known as room_tundra_placeholder, uses Snowdin sprites and consists of an ice puzzle. If the protagonist attempts 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 300 ==
 
Room 300, also known as room_ruins12B_old, uses Ruins sprites and is similar to room 13, 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 301 ==
 
Room 301, also known as room_tundra_rollsnow, has a small snowball whose mechanics are similar to the Ball Game in Snowdin Forest. If the protagonist pushes the snowball, it gradually grows until it reaches maximum size. This room does not connect to any other rooms.
== Room 302 ==
 
Room 302, also known as room_water7_older, is an old version of the room before the second Undyne encounter, and the game crashes when entered 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 combust when the protagonist interacts with them. This room may represent an unfinished puzzle similar to the torch puzzles in The Legend of Zelda. Leaving this room crashes the game.
== Room 303 ==
 
Room 303, also known as room_meetundyne_old, 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. This room also has the scene in which Papyrus talks to Undyne and uses the same dialogue as the final version of the room. 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 304.
=== 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 304 ==
 
Room 304, also known as room_water_mushroom, has 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 305) 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 303, the right exit connects to room 305.
=== 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 305 ==
Room 305, also known as room_monsteralign_test, is black and has a Memoryhead that disappears.
== Room 321 ==
Room 321, also known as room_empty, is a black room.
== Room 326 ==
Room 326, also known as room_of_dog, is the Annoying Dog error room if the SAVE is invalid. The unused soundtrack mus_sigh_of_dog or mus_dance_of_dog plays in this room.
In the Undertale Demo, room 271 replaces this room.
== Room 327 ==
Room 327, also known as room_quizholder, is a black screen with Mettaton and Alphys, as seen in Mettaton's quiz show. Mettaton waves while Alphys looks on nervously. The player can do nothing in this room.
== Room 328 ==
Room 328, also known as room_friendtest, is gray and was used to test the scene before the Asriel Dreemurr 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 329 ==
Room 329, also known as room_bringitinguys, 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 333 ==
Room 333, also known as room_asrieltest, is black and was used to test Asriel Dreemurr'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 334 ==
Room 334, also known as room_afinaltest, was used to test Asriel Dreemurr's "Angel of Death" animation. The SOUL is the same placeholder sprite seen in room 333. The SOUL can move freely around the screen and is always in the foreground.
== Room 335 ==
Rooms 335, 336, 337, and 338 have varying results based on the game version.
Room 335, also known as room_dogshrine, is a room introduced in the Playstation version, where it is accessible in-game. This room is an inaccessible room in PC versions after v1.05 as well as the Switch and Xbox versions (room 336 on Xbox). This room leads to the Dog Shrine.
This room did not exist on versions prior to v1.05.
== Room 336 ==
Room 336, also known as room_dogshrine_ruined, is a room introduced in the Switch version, where it is accessible in-game. This room is an inaccessible room in the Xbox version (room 337 on Xbox). It contains the ruined dog shrine from the Switch version.
This room did not exist on the PC or PlayStation versions.
== Room 337 ==
Room 337, also known as room_dogshrine_mewmew, is a room introduced in the Switch version, where it is accessible in-game. This room is an inaccessible room in the Xbox version (room 338 on Xbox). It contains the Mew Mew doll from the Switch version.
This room did not exist on the PC or PlayStation versions.
== Room 338 ==
Room 338, also known as room_of_bog, is an unused room introduced in the Switch version. This room is an inaccessible room in both the Switch and Xbox versions (room 338 on Xbox). It is an empty black room.
This room did not exist on the PC or PlayStation versions.
== References ==
de:Unzugängliche Räume
es:Cuartos Ocultos
fr:Salles Inaccessibles
pl:Niedostępne Miejsca
pt-br:Salas Inacessíveis
ru:Недоступные комнаты
zh:無法前往的房間