I played though Undertale, and listened to the soundtrack. There is one song on the soundtrack that I didn't recognise from the game. So where does "Song That Might Play When You Fight Sans" appear in the game?


3 Answers 3


Song That Might Play When You Fight Sans is a red herring

The song in question is exclusive to the soundtrack. The song appears nowhere within the game itself, and is intended to throw you off from noticing the real song that plays when you fight Sans:

Megalovania, which has some special significance due to its use in other forms of media Toby Fox has been involved with.

As a side note, some mods or fangames have been created that show what a comically simple Pacifist run Sans fight would be like, some of which utilize the song as the battle music for said fight.


It doesn't.

As far as we know, in v1.1, this song is never played in game. Indeed, it doesn't even ship with the game.

  • 2
    Conversely the game files have several files that aren't on the soundtrack, such as mus_dogroom.ogg.
    – badp
    Commented Mar 6, 2016 at 20:39
  • 2
    And for an example of music that ships with the game but isn't actually used, mus_kingdescription.ogg
    – badp
    Commented Mar 6, 2016 at 20:42

This song can only be found in the game files, it is not used in any of the gameplay even if you try to hack it. Some people suggest it might have been a previous and now disused version of MEGALOVANIA (the soundtrack that plays when you actually fight Sans). The soundtracks are very similar when you break down the audio - there are many patterns as shown with the relation to Waterfall, Spear of Justice and Ruins. This is very possible because as good a game as Undertale is, there are still minor flaws and random secrets such as this audio piece that was discovered to serve literally no purpose in the game.

  • 2
    As mentioned in my answer, Megalovania is a song that existed for quite some time before Undertale did, used in two of Toby Fox's previous works. Song That Might Play is certainly not a prototype of Megalovania. Further, as badp mentions, the song isn't actually even included with the game, it's only part of the soundtrack. Commented Aug 1, 2016 at 20:31

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