I saw this question about how to open it, and I wondered what is inside it.

Has anyone seen this door? What exactly could be behind the mysterious door?!

I tried opening it but couldn't. Even tried lighting up the mushrooms with different sequences. Perhaps it is supposed to open in the second play through? Or maybe, you need to buy the key from those 2 girls [Bratty and Catty] who were selling trash?

Mysterious door

Seeing the tag of Undertale, fills me with determination.

  • 2
    This is not a duplicate question, the "dupe" question is "how to open", while this is a "what is inside" question.
    – ave
    Jan 23, 2016 at 22:08
  • 2
    @ardaozkal Good point. :/
    – Haider
    Jan 23, 2016 at 22:11
  • 1
    @ardaozkal Questionable. Until your edit, it was almost entirely "how do I open it." Even now, it's still mostly "how do I open it." Making it only "what's inside" would probably involve replacing almost the entire question. Jan 23, 2016 at 22:32
  • @MikeKellogg see the title.
    – ave
    Jan 23, 2016 at 22:34
  • 2
    @ardaozkal I do see the title. The contents of the question are far more significant. Jan 23, 2016 at 22:36

1 Answer 1


Behind the Mysterious Door lies a joke "developer" room. It contains only a few objects, each of which can be interacted with to show some text. The Undertale Wikia has a list of all of the text that the room contains.

Here's what the room looks like:

Screenshot of room contents

  • 3
    It was a very anticlimactic secret.
    – user1337
    Jan 25, 2016 at 4:58
  • 2
    Oh?! And I thought this room had cure to Cancer or something.
    – Haider
    Jan 25, 2016 at 7:28
  • It has Tony Fox himself inside twice, first to the left of the entrance and second straight in front of you when you enter, sleeping on the carpet. Apr 27, 2022 at 20:37

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