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From The Cutting Room Floor
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This page details one or more prototype versions of Undertale.

To do:
  • A few more differences to cover as well as unused content. Specifically, this stuff.
  • Older versions of the demo, dated on or after May 23, 2013. The latest version is dated June 8, 2013.

Developer's Message

It's cool that you like my game this much.

Yes, I know these are easy to decompile... You can edit Yume Nikki and OFF in RPG Maker as well. This isn't really any different.

My only wish is that you don't spoil the game for anyone else.
Wait for everyone to discover the secrets in here by themselves.
Otherwise, there will be no replay value :(

I'd also appreciate it if you held off on significant modifications before the full game is released.
I'll most likely be updating some things about the game that might make it interesting to play with.

I'll be watching...

Ha ha ha.

Toby Fox's choice words for those who decompile the demo. Located in a script called "Attention, Hackerz".

Demo Differences


Demo Final
Undertale (Demo)-Intro.png Undertale (Final)-Intro.png

The Loox was changed to a Boss Monster. The demo's intro image would end up being used later on in the final version, when Flowey alters the game after crashing it.


Demo Final
Undertale (Demo)-Beginning Area.png Undertale (Final)-Beginning Area.png

The path leading to the exit was changed to look more like an exit, while the non-path not leading to the exit was changed to look less like an exit. In addition, the exit received a more ornate design in the final version.

Demo Final
Undertale (Demo)-Beginning Area2.png Undertale (Final)-Beginning Area2.png

Quite a bit was changed in this area — notably, the stairs were made more detailed, the shadows were shortened, more leaves were scattered around, and the vines above the exit were removed.


Demo Final
What a cretin,
torturing such a
poor, innocent
What a terrible
creature, torturing
such a poor,
innocent youth...

This text is seen when the player first meets Toriel, where she talks down on Flowey for harassing the player. The final version changes the word "cretin" to "terrible creature". This was almost certainly changed because the demo version's line doesn't fit Toriel's character at all.



He doesn't have the option "Dinner" which is the option used to be able to spare him in the final, which means that you can only run from him or fight him. They can be spared, but only by reducing their HP first. Might have been from a possible limitation at the time, as you have to collect green carrots to allow him to be happy with you, but that would mean that Toby would've had to code in new functions to make it work like in the final.

In the demo, the "Eat" act will kill weakened Vegetoids, earning EXP and advancing the kill counter. The final replaces this with "Devour", which only eats them a little bit, ending the battle (technically) peacefully.

The Vegetoids in the switch room reappear even when killed, and even when the kill counter is maxed out and there are ostensibly no monsters left in the Ruins at all. Killing these Vegetoids repeatedly will eventually confuse the demo out of the No Mercy path and back into a Neutral path.


One of the most important functions of the game never appears in the demo, which is that a monster's name turns yellow when they can be spared in the final. This means that it is impossible to tell if a monster can be spared or not in the demo.

In the demo, it's possible to earn EXP by sparing injured monsters. This feature doesn't exist in the final game: given the nature of EXP in the game, the demo's behavior wouldn't make sense and could unfairly lock an unsuspecting player out of the best ending.

In the demo, Flowey and Chara have the ability to change the game's instruction manual based on the course of events the player takes. This was removed from the final version due to software limitations, although the graphics used for it are still in the final.

In the final version, attempting to name the fallen human things such as Sans or Alphys would be prohibited, and naming the fallen human Gaster would restart the game. Other easter eggs were added as well, each relating to the name of a character. This does not function in the demo.

Unused Music

Grandpa Semi

  • A variant of the intro to Mettaton's battle theme with the odd filename "grandpasemi.ogg". In 1.001 of the final game, this is used, renamed to snd_grandpatemi. It plays when Temmie is denied Temmie Flakes.
grandpasemi Mettaton Battle (First few seconds)

Start Menu 1

As the player progresses through the game, the main menu music gets progressively more complex. In the demo, music tracks are overlaid on top of each other instead of being all in one file. They are slightly different from the final version.

The first track has slightly softer drumming.

Demo menu1 Final menu1

NOTE: "menu1.ogg" was renamed to "mus_menu0.ogg" in the final, and each subsequent song was decreased by 1 as a result, but for ease of reading, each song will be referred to here by their demo name. There are only 4 menu variations in the demo, but 7 variations in the final.

Start Menu 2

In the demo, "Start Menu 2" is the bass accompaniment to "Start Menu 1". In the final, the bass and "Start Menu 1" are merged together.

Demo menu2 Final menu2

Start Menu 3

In the demo, "Start Menu 3" is a NES-sounding instrument. In the final, it's "Start Menu 2" with a piano playing the "Start Menu 1" layered on it.

Demo menu3 Final menu3

Start Menu 4

In the demo, "Start Menu 4" is made completely of orchestral instruments, with no NES-esque instruments. In the final, "Start Menu 4" is "Start Menu 3" with yet another NES instrument layered on.

Demo menu4 Final menu4

The demo's "Start Menu 4" sounds very similar to the final's "Start Menu 6".

Demo menu4 Final menu7