Undertale

Undertale
Developer: Toby Fox Platforms: Windows, Mac OS X Released internationally: September 15, 2015 This game has unused areas. This game has a hidden developer message. This game has unused graphics. This game has unused music. This game has unused text. This game has revisional differences. This game has a notes page This game has a prototype article This game has a prerelease article

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

To do: For a fourth wall bending game like this, it should be no surprise there's a lot of hidden stuff in the code. Cover the demo as it appears to be an earlier version. Lots of stuff on this subreddit and this website

Unused Music

mus_kingdescription

A regal-sounding variation of the Game Over music that isn't heard anywhere ingame. Likely intended for a scrapped scenario involving Asgore.

mus_f_part3

Another variation of Flowey's boss music. 0:20 onwards is used for scene transitions, but the beginning goes unheard in normal gameplay.

abc_123_a.ogg

Hello. Hahahahaha. 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! Hahahahahahahahahahahahahahaha.

A soundfile of 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.

Unused Graphics

spr_torielboss_suicide

A duplicate of Toriel's "hurt" image with a ...spookier file name. This file was present in the demo as well.

splash

This splash image was used in the demo while the game was loading, but isn't in the final. This image is only in the OS X version of the game.

(Source: Dr. Yay)

Flowey's Message

• 
• 
• 

In the demo, Flowey had the ability to edit the instruction manual depending on your progress in the game. Unfortunately (or maybe fortunately), when the project was ported to GameMaker: Studio, this became impossible. The files are still left over from the demo.

Unused Text

LOOLLLL IF YOU CAME TO THIS PART OF THE CODE TO SEE WHO I HAVE A CRUSH ON YOURE OUT OF LUCK

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.

 [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
                situation...
 [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. There's no known way to trigger this ending in normal gameplay. The actual script data contains control codes to change Sans's expression, represented here by bracketed text.

Developer's Message

Hidden within the game's sprite data is a crudely-written note addressed to sprite rippers, telling them to wait a year before uploading full sheets online (with some exceptions).

Unused Rooms

To do: The rest of the rooms found here. Add screenshots.

room_gaster

The room displays a message in the Wingdings font and has strange electronic buzzing sounds playing in the background. One of the decoded messages reads:

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?

(Source: Reddit r/Underminers)

TESTROOM

A room that seems to test out the in-battle dialogue boxes.

Version Difference

In the Windows version, the monitor in Alphys's lab follows your movements, however is only a static image in the OS X version.

Windows	OS X