Viewing Mod
The Binding of Undertale
TBOI x Undertale Crossover Mod
Created 2 years ago

Get the AB+ 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!

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):



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 7745

- 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)


- 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)

help!! I went to install it and its not working! how do I download and install it?
Well, perhaps you just didn't buy at least Rebirth.
hello, i have some trouble with this mod, only thing i get is backgound , new skin for character ( except dummy who still have dark isaac head) and flowey sound in top of devil room.
i didnt get undertale music, item, dummy full skin, timmy shop, and maybe other thing i dont know (i restart the game so i didnt unlock everything) does someone have a solution please ? thank you very much for any answer who can help me :0
By the way i play on rebirth version and i put rebirth mod on it.
So what's the difference between the "Rebirth-only" and the
"Afterbirth" version?
The Rebirth version only has Frisk, Asgore, Mettaton, sans, Toriel, Papyrus, Undyne, Mad Dummy and Gaster. It is also incredibly buggy. The Afterbirth version includes almost every Undertale main character, but Asriel, Monster Kid, and Muffet are in a separate character pack.
i downloaded the but i only got the asriel muffet and monster kid folder and the rebirth how do i get the other two?
antibirth is rebirth, so i think that the rebirth version might work
help i cant download it it asks me what do i want to usd to open it what do i do?
May I ask how you did changed the ISAAC thing on the title to UNDERTALE? I'm making my own modpack for the game, but I don't know how to change the title.
I don't know the Sprite directories by heart, but there is a folder named 'main menu' or 'title menu' somewhere in the UI folder which contains the Sprite for the title logo.
Is there a way to temporarily turn off the music part of this mod and put it back to the original Binding of Isaac music? I love the mod and its features, but I m honestly getting a little tired of undertale music and would like to change the music back to the default. The rest is wonderful, thank you!
tu va dans le dossier steam , steamapps, common, the binding of isaac rebirth, ressource, dans une autre fenetre tu ouvre le zip que tu obtien en telechargant sa, va dans le dossier rebirth only, copie tout se qu'ily a dans le dossier et colle le dans ressource
I do not know how to put it in my binding of isacc rebirth for mac
¡Hello! I love your mod!
I got rebirth... Rebirth is buged or something, i wait for the next upgrade. The Binding of Undertale
how do u download the basic version
Chara is ??? you have to beat the game a couple of times to unlock her.
Love these mods, and love this site
Try and add Gaster! just a suggestion
January 20, 2017 - 9 months ago

A new animated Planetarium theme (from Antibirth) is now available!

There is a new DLC search filter on the Browse Mods page.

Added the 50 new babies from Afterbirth+.

The What's New sheet will try to get your attention when there is a new site update.

Fixed some mod icons not changing after being updated.