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(Both of the above notices were made by ThomasThePencil. The sprites within them were a collaborative effort between ThomasThePencil and SkribblySpence.)

Barrier Blocks is an AU involving Minecraft YouTubers created by a user named ThomasThePencil. It follows a 15-year-old boy named Aston as he ventures through the Underground under the guise of "curiosity", although nothing is quite as it seems in this new, yet familiar world...


NOTE: More will be revealed as the reboot of the AU begins and progresses.

The Ruins

With a few now-defunct puzzles and not much lighting, the Ruins are the first area Aston encounters on his new journey. Heat lamps (with Jason controlling the fire that lights them) dot the caverns, as do several hints of the past. Jason's home lies at the end of the Ruins, with the exit door not far behind it.


Marked as the second area Aston takes on, the immediate area outside the Ruins door is a dense forest. It's also extremely cold, to the point where Aston has to try and warm up almost immediately after stepping outside the Ruins. With a good deal of inhabitants and a town called Hailton at its edge, it's probably worth sticking around...mainly because legally, it is safe haven for fallen humans should they reach Hailton. The main "threat" here is the Snowfall Guard, led by Thomas and Shelby and consisting of humans and monsters alike.


NOTE: More will be revealed as the reboot of the AU begins and progresses.


Aston v4.5
UT Role: Frisk

With an interest in sailing and plenty of stories to tell, Aston is the protagonist of the AU. He came to Mt. Ceplin after a long chain of events, with the result presumably being...less than desirable.

Information and Trivia

  • Came to the mountain supposedly out of curiosity, although it's fairly clear that's not all there is to it.
  • Is slightly scared about what he might find in the Underground, but pleasantly surprised by what he does first.
  • Very quick to accept any form of platonic affection, but gets extremely flustered if someone flirts with him.
  • Is very optimistic about what he can do to help the Queen of the Underground after Jason's fight, although at that point, the state of the Underground...hasn't really sunk in for him yet.
  • He has an affinity for sailing and wants to travel the ocean at some point in his life.
  • As noted in Part 9, Aston feels as though someone is "constantly making him do stuff" while in the Underground. He describes them as a sort of invisible force...person...thing, though it's still not entirely clear who this might be or why they're doing so.
  • His favorite food is milk chocolate. He thinks white chocolate is weird.


BBDongusBattle REBOOT
UT Role: Flowey/Asriel

A friendly squirrel with a scarf and bowtie, Dongus is the first new pal Aston meets in the Underground, although not all is as it seems with this furry little friend...

Information and Trivia (Dongus)

  • How he came into existence at all is unknown, although some information from Cory reveals he had a past life as Ross. Dongus says a man named Andy has done a lot for him, though what these good deeds are has yet to be explained, and that explaining why he's a squirrel would likely cause Andy to get uspet.
  • He's implied to get a little crazy if left alone with a surface human for too long.
  • He's nowhere near as cunning --- or evil --- as the original Flowey, and really doesn't have any big plans for Aston. Or does he?
  • He may or may not have a rivalry with a broom. Yep.

Information and Trivia (Ross)

  • Not much is known about Ross other than that his death led to the birth of Dongus somehow. How he died and why has yet to be revealed.
  • Has a cat named K.P. that Tim takes care of in place of Ross.
  • May or may not have had a plush squirrel toy. A big one. Make of that what you will.


BBThomasBattle REBOOT
UT Role: Sans

The most agitable scientist you'll ever meet, Thomas is one of the bigger dogs on campus around Snowfall. With a slight air of mystery to him and a clear distinction from the others, those uninformed will find themselves eternally puzzled due to his own importance in shaping the events that have transpired...

Information and Trivia

  • His SOUL is a lightish grey --- darker than any monster SOUL, yet far less vibrant than any normal human SOUL. Furthermore, his body is displayed as grayscale in-battle and in his talksprites, even though he himself is very much in full-color.
  • He possesses an array of difference devices and doohickeys --- some intended to stop humans, others to help the Underground. Which ones do what, nobody knows...except him. And those he trusts. And the people unfortunate enough to try anything stupid. Also probably everyone else, with the level of publicity he once used to get.
  • He is far from enthusiastic about the idea of another human falling into the Underground, though why this is the case is not clear.
  • He seems to be able to hear Miss Mystery.


Shelby v6
UT Role: Papyrus

Bouncy and bubbly, and tons of fun! Shelby's the commandress of the Snowfall Guard, and she's more than willing to help Aston along throughout his journey.

Information and Trivia

  • She doesn't see eye-to-eye with some of the guard on the human policy, and believes any fallen human should be subject to the same deal the rest of them are. If they're good, they can stay. Of course...not everyone agrees with this, and so the Captain is much more popular among the guard itself. She's got the attention of a lot of the residents of Hailton, though, even if not all of them favor her stance.
  • She's deathly scared of killing. Very few of the Underground's residents actually know why.
  • There's an odd blotch on the back of her hair that's a different shade of red compared to the rest.
  • She hasn't had white chocolate in years.


UT Role: Asgore

As the Queen of the Underground, Jess is hardly in the best position. With several kills and a bloodthirsty kingdom, and the final SOUL now within reach, she has to decide: it's either her subjects or her ideals and morals.

Information and Trivia

  • She has the highest LV out of everyone that resides in the Underground, at a considerable LV 5.
  • Her husband, Jason, is believed to be dead after heading for the Ruins. She refuses to believe it, though, and wants to believe he's still there somewhere, waiting for the moment when he can come back.
  • She's actually not exactly able to fully utilize her magic --- as such, she wields a staff as a way to channel her raw magic into powerful attacks.
  • While she doesn't want to kill Aston, she also needs to take into account the hopes and dreams of the entire Underground, and given the fact that a lot of the Underground is out for blood as a result of the past...
  • She wrote the teen romance novel series "Midnight."

Other Roles

NOTE: These are all defined very loosely.

Doggo: SethBling

Mad Dummy: Fit

Nice Cream Guy: Boom (OC)

The Annoying Dog remains in his role, and is just as ridiculous as in canon UT.

Gameplay Changes

  • The battle UI has been revamped to account for the new size ratio and style of the battle sprites.
  • To replace the fallen humans' items, as all of the fallen humans and their belongings are in Jess' castle, a system of item crafting allows for a choice in your weapon and armor progression. You can even craft consumable items. The materials can be gained by sparing enemies. Some armor and weapons can also (or only) be bought in shops.

Official Soundtrack

Due to the creator of the AU being a musician, there's a lot of music available for the AU. Unless otherwise stated in a specific song, all motifs are original. Here's a link to the full soundtrack.

Some additional notes about the OST:

  • Extra songs (marked with an EX before the number) are either unheard in canon gameplay or very difficult to find.
  • For the song "Hotel", the full title is "Do You Seriously Call This A Hotel, I Didn't Even Get A Coloring Book or Some Crumpets"
  • "Shelby's Story" and "Feeling Hopeless" are mutually exclusive. You will never hear both on the same route.
  • The two songs at the end of the current playlist are incredibly spoiler-heavy, but have been uploaded because their context and purpose is important.

Sprite Gallery [REBOOT ONLY]


  • The AU was just titled "Undercraft" at first conception. The name was changed fairly early into production and became what is now known as "Barrier Blocks."
  • At one point, Jess and Jason's roles were going to be swapped.
  • While it currently only has a sprite comic, the AU is largely built around being a game and will hopefully be getting a game sometime in the future, although it will not be created for a while due to the sheer scale of the AU.
  • Roleplay series like Minecraft Diaries still exist in-universe, and Jess actually managed to finish up the series' third season in this universe (an unmodified copy of Minecraft made its way into the Underground beforehand and quickly became mass-produced) and released the whole series on DVD for all to watch. The same is true of several other series she's in charge of.

Comic Part Links (/r/Undertale)

Preboot Ruins

  1. Jason and the Squirrel
  2. Introductory Discoveries
  3. Statues and Scribbles
  4. An Entertaining Encounter
  5. Someone To Call "Dad"
  6. Subtle Insecurities
  7. Emotional Detachments


Parts whose names are italicized are parts that have not been released yet.


  1. Going Nuts
  2. In Your Defense
  3. Chickenscratch on Cobblestone
  4. Comedic Force
  5. (Un)Written Expression
  6. The Fallen, The Dad, and the Door Girl
  7. * Too hot.
  8. 101 ways to not make a good first impression.
    1. A Frosty Start
    2. You're in the big leagues now.
  9. Back and Forth
  10. A Couple Of Issues