Viewing Mod
The Binding of Undertale
TBOI x Undertale Crossover Mod
Created 5 years ago

Get the AFTERBIRTH+ version here:

Thank you very, very much for the Mod's overwhelming reception and 50000+ Downloads!

This mod replaces characters, music, bosses and floors with Undertale content! Enjoy!

by tipo19 and Opscat

Talk to us!

  • Our Subreddit!

  • Q: Do I need Afterbirth for this to work?
    A: No. Inside the folder, you can see there is a "Rebirth only" folder.

    Q: Where's Toriel, Asgore and Chara?
    A: You installed the Special version. Re-install the mod, but only Install the Basic version, not the Special one, and you'll get those characters.

    Q: My game Crashes!
    A: Install the mod, then delete Costumes2.xml. Be aware that this might cause characters to change appearence
    when collecting some items.

    Q: I'm in Snowy/Waterfall and the screen is pitch black!
    How to fix:
    Go inside resources/gfx/Background and delete the "Black" images. Those being: 8bitclouds_64,8bitclouds_64_black,8bitclouds_642,8bitclouds_643,blue_overlay and orange_overlay.

    Q: I see a credits page, but not the Challenge page! Where is it?
    A: If you want to see the challenges, just go inside gfx/ui/main menu and delete challengeph.png

    Q: Is this compatible with Mac/Linux?
    A: As far as we know, it's compatible with mac. It's super buggy with Linux and we plan on fixing of it later.

    Q: I found a bug! Where can I report it?
    A: Either Private Message me through Steam or the mod's blog.

    Q: Can I suggest/submit stuff?
    A: Yes! Either go to the mod's blog or post a comment in this comment section.

    - The mod can be very glitchy on Linux and Mac.

    - The Rebirth-only version is very early so expect glitches.
    (Example: No Gaster Blaster. For some reason, rebirth ignores the familiar folder.)

    _ In Snowy Rivershore and Waterfall, the screen might go black, but you can still hear the sound. Read the FAQ, you can find the answer there.

    -Bugfix for Mac:

    -More item reskins. (Taking Suggestions!)
    -Waiting for Afterbirth+ !!!!

    SwingPoynt v2:
    iVertrox (Spanish):


    HOW TO INSTALL VIDEO by Zenofirex:

    Special Thanks to:
    Patkall - Sprites
    FAz - Sprites
    SoaringSparrows - Original Concept
    IKARUS - Song Credit
    /u/Haylex - Tem Shop Mod
    Draexzhan - Miscellaneous Item Sprites
    reijigazpacho - Logo
    Felix ( - Nightmare Sprites and the Omega Flowey boss
    Sophomore - Miscellaneous Item Sprites
    /u/otherhand42 - Miscellaneous Help
    engineerthecowboy - Rebirth Testing
    Toby Fox - Undertale


    x 8427

    - 20+ New items and 3 transformations, by the talented FAz!

    - Community Update: 20+ items and a Flowey transformation, by the amazing /u/Patkall! Thank you!

    - Fixed compatibility with the newest Isaac patch.

    - More items

    - New version whenever Afterbirth+ Hits

    - Fixed Rebirth Compatibility

    - Rebirth Support! (Thanks to engineerthecowboy for testing!)

    - Community Made items!

    - More items, like Muffet's Pet and Lil' Whimsalot!

    - New character: Mad Dummy!

    - Made it easier to understand how to install/know what version you're using.

    - Small item replacements.

    - Balanced some stuff.

    - Fixed Special Version having a hybrid of Gaster and Temmie.

    - Two New Characters, Gaster and Temmie.

    - Two new end bosses, Omega Flowey and God of Hyperdeath Asriel

    - HP up item reskins

    - Some music added

    - Napstablook now Starts with Dapper Blook

    - Frisk starts with Purity (Soul Colors)

    - Between level (”Nightmare”) sprites, courtesy of @stupid-doo-doo-butt

    - Only a small amount of items now change your character.

    - Asgore, Sans, Mettaton, Toriel, Asriel and Undyne have new costumes wich will help prevent their appearence to change.

    - Fixed some naming stuff

    - Made the Character menu less messy

    - Toriel starts with proper items

    - Blue womb is not dunked up anymore

    - Characters don't have their items because you didn't unlock them was fixed

    - Napstablook glitches when picks up a item was fixed

    - Frisk doesn't have Isaac's heart, just <3

    - Papyrus lost 1 heart container inside his spaghetti

    - Mettaton has better bombs and Tech.5 (not tech 2)

    very good mod, but the sprites doesnt change when we get items, the sprites of the coins are broken, and I dont have the starting items (ex: chara's knife)
    anyone have a idea for fixing this?
    Welp looks like im going to have a bad time
    guys, need help. i have tboi rebirth. so, i can't see anything on waterfall stage. i have HUD, but i cant see neither my character, nor whole stage. it's just nothing.
    could anybody help me with solving?
    is only the friends of creator writed it work?
    i want this mod but i cant install it
    i go into the common and there is nothing like the binding of isaac rebirth please help ;(
    i love it ………………………...
    is this compatible with the binding of issac mod loader?
    Well, i did it right and it doesnt work. game do not see mod and do not change at all :/
    Yep, i know about instruction, it is helpless.
    Am i wrong with something???

    p.s. i am from russia, there is my comrade in comments with same problem u no
    when you like tboi and ut this is a great game crossover its pretty great
    love itlove itlove itlove itlove itlove itlove itlove it
    Kind of. It' functions but you cant play as The Forgotten no character swaps him and the mod fundamentally breaks him entirely.
    January 16, 2020 - 8 months ago

    Maintenance complete! We have moved to a new web server! Speed and stability should be improved. If you notice any issues, please mention them in our Discord server.