Game Theory: Gaster's Identity REVEALED! (Undertale)

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  • Published on:  Sunday, February 26, 2017
  • Flowey in MINECRAFT! ►
    Part 1 - Who is W.D. Gaster?! ►►

    It's part 3 of my Undertale trilogy. We finally get to the bottom of the Gaster mystery with our greatest weapon of all -- SCIENCE! We've done a good job of connecting Sans to the Undertale mystery but what about Papyrus? How does he fit into all this? Well Papyrus is a lot less innocent than he appears. So crank up the Megalovania and stay Determined, it's the FINAL Game Theory on Undertale!

    (And btw: Thanks for all your incredible support on this series! I hope you've enjoyed it as much as I've enjoyed making it!)

    Gaster sprite by Kazoomageddon on Tumblr ►

    Become a Theorist! ►►
    Twitter: @MatPatGT

    THANKS to literally ALL the editors for their amazing work on this video!

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  • Best Pearl

    Best Pearl

     2 years ago +23803

    You didn't mention it, but the Annoying Dog has been confirmed by Toby Fox to represent him.
    So if the Annoying Dog stole Papyrus's special attack, that means that Toby Fox intentionally chose not to reveal what the attack was but wanted us to know that he did remove it.

  • Noeal Noeal

    Noeal Noeal

     17 hours ago

    Maybe Sans and papyrus were once humans but they did not managed to exit and died and their human souls were one of the hearts and they became a skeleton?

  • Kris



    mostly undertale=deltarune= nutdealer

  • Emery_20275


     yesterday +1

    Did you know that the human brain can hold up to 2.5 MILLION megabytes?

    It doesn’t even fill in an ENTIRE LIFETIME!!!

  • Senior Pug

    Senior Pug

     2 days ago

    Truth about papyrus he’s a 4 year old ghost in a skeleton of a dead human

  • highland coo

    highland coo

     2 days ago

    So I think Sans and Papyrus were originally created by Gaster to be experimented on. Like guinea pigs or lab rats. Both of them became smarter than Gaster wanting them to be. And he saw Sans as a colleague, someone as smart as him. The same species, the same mindset, and a willingness to follow orders from a creator. Like all artificially made things. Perhaps him and Alphys had a falling out over the determination experiments, or the use of what Alphys saw as his children? And out of spite, he made Sans his new assistant. But the two scientists came to an agreement, and worked as a three.
    Gaster didn't experiment on Sans, due to his low HP. And he didn't experiment on Papyrus for many possible reasons.
    Did Gaster start seeing them as his children?
    Did Alphys refuse to work with him, if he used Papyrus as a test subject?
    Did Sans break from his mindset to follow orders, and snapped at his creator for harming his 'brother'?
    Or was Sans able to help Papyrus escape, and find a less dangerous life? Since we all know that Sans' only goal in life, is to keep his little brother safe.
    If any of these were true, Papyrus may not remember the training and abilites Gaster taught him, may not remember how he came to be in the underground. He may not even know who Gaster is. And Sans kept it that way, so Papyrus was in no danger of being hurting, lost in time, or having traumatic memories of torture or experiments.

    But hey that's just a theory! A gaaaammmee theory!

  • marisa jones

    marisa jones

     3 days ago

    and then came deltarune

  • Luke the minecraft player 3.0

    Luke the minecraft player 3.0

     4 days ago

    If you said sans is ness then if sans is ness does ness use da hand you said sans uses???

  • Luke the minecraft player 3.0

    Luke the minecraft player 3.0

     4 days ago

    I love gaster and this true cause I got same results on checking him

  • Flowey Sans EXE

    Flowey Sans EXE

     4 days ago

    I don’t think that’s true because in the secret room with gaster in it when you leave it you still see sans and papyrus

  • Benjamin McKiddy

    Benjamin McKiddy

     4 days ago

    I have something to add to this
    Sans and pyres have 1/2 brains

  • frostbite fan

    frostbite fan

     5 days ago

    Sorry matpat but this is a matter of your sans is ness thoery. Ok so you know that picture in the workshop. it says "SANS AND 3 FIGURES YOU DONT RECOGNISE". Shouldnt it say four people you dont recognise because how would you know sans as a human. Also if sans were to be ness he wouldnt be able to do magic because humans cant do magic also he so call turned into a monster so where did he get the magic from? Also when you do the pasfist ending papyrus askes what the yellow cricle is and sans says we call that the sun how do you know that he didnt learn that in another timeline???
    Thank you for your time
    Also the gaster thoerys sound more accurate.

  • LeDasOn


     5 days ago +1

    That would make sense because Sans has a Blue and Orange LEFT Eye and that could mean that Papyrus has either an Blue, Orange or Both RIGHT Eye too

  • Pringle The 3rd

    Pringle The 3rd

     5 days ago

    Gaster there dadster

  • Βαγγελης Μοσχογιαννης

    Βαγγελης Μοσχογιαννης

     5 days ago +1

    Sans and Papayrous is not Gaster but they are Gasters sons

  • Jake undertale dreamurr

    Jake undertale dreamurr

     5 days ago

    So it means dyslexia would me a left brain ;~;

  • Emmett F

    Emmett F

     5 days ago

    Change a to a U and get rid of the S at the end

  • Emerson Bixby

    Emerson Bixby

     6 days ago

    I was surprised but my friend who dosent know what you are talking about

  • Tyler Sprik

    Tyler Sprik

     7 days ago +1

    This is all correct. Sans is Ness because Ness died and went underground as a soul, then Gater shattered himself and the left brain fused with Ness to create Sans, while Papy simply only has Gasters right brain. Therefore, Sans it strong because he has a superstrong monster soul as well as a human soul, fused. Papy doesn't. Get over it. Paps is a starman, and has two normal monster souls. That's why Gaster shattered when Flowey didn't, Gaster was a monster and determination melts monsters. Flowey was just a plant. Based on my calculations, this puts Sans and Flowey at EXACTLY THE SAME POWER. Deltarune, though, is an alternate universe of Undertale, the whole SANS WAS MY FATHER is because Sans was aware of different timelines. Also, Gaster Blasters are residual from Gaster, the determination gave him the weapon. Flowey’s hyper goner was less concentrated because his Gaster connection is less concentrated.
    End theory.

    I will await my invitation to the game theorists

  • oussaid abir

    oussaid abir

     7 days ago

    U used the genecide and pacifiste both of them are in a difrent time and story choose one of them