Viewing Mod
The Binding of Undertale
TBOI x Undertale Crossover Mod
Created 4 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 8231

- 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)

is there any option to not dowanload this by java?
the rebirth only folder doesn't work
do i need afterbirth to play asriel? If not,i cant play these characters. My game crashes every time after loading the file with asriel,muffet and monster kid. (im playing on rebirth)
it doesn't work for me. i put all the asgore,toriel, and chara files in resources but its still normal binding of isaac
Is there a Rebirth version, or is it only for afterbirth/afterbirth+?
I can't open the game. Every time I try to it tries to download itself again what am I meant to open it with
oh by the way im trying to download it for tboir\thebindingofisaacrebirth
I like Undertale and Binding of Isaac quite a lot, and seeing a mod that mixes the two is the best thing ever.
Really hope you guys continue this, it's really good!
Мод почему-то никак не виден
или я тупой и не правиль но делаю что то
windows breaks every mod on this website
it's not working for me is it because I'm on Mac?
It still works on mac. Im on mac so just try some different things and hope it works
I found the problem I didn't have Afterbirth+
In the files of the mod there should be a rebirth file i think. I used it before i had afterbirth and i don't have afterbirth +. So look inside the files
I can't open the game. Every time I try to it tries to download itself again.
It's already out for Rebirth and Afterbirth.
You just need to download the mod and you'd see inside that the Rebirth version is in it.
i don't know how to get it to the binding of Isaac....
Go to Documents, My games, The binding if Isaac afterbirth + mods.
After installing this mod it game is crashesing (Mac OS)
Now I wonder if there will be a Deltarune mod?
Oh. My. God.
Same. In my opinion, Ralsei is quite a good character in the game.
In the Rebirth version apparently Frisk and Toriel's health are messed up making Toriel OP early game while making Frisk hard.
i love this mod so much, but it wont stop crashing. i havent been able to finish a run yet purely because every challenge room or boss rush or even sometimes just normal rooms, it crashes and restarts me at the beginning of the floor. please fix this
im on mac but why download i dont want to download
wow ! under tale was vary fun and so is the binding of aftherbirth + ! i am much glad that you will have made this game for us ( the commune ) to play ! keep doing what you are doing ! and ps #yolo !!!
please make it not a winzip file because my winzip expired
Try using Winrar. If you're already using Winrar then how could it expire? Winrar is free and basically can't expire, you'll always be able to use it.
Welp. Can't download it, im sad
*cri cri cri*
I like watching it, but won't install
Sans could fit better with the lost.
This is pretty popular, but I'm not a fan.
I Just Played It Not Recording, Planning It!
Hi hello hello there, uh, was just thinkin', sans replaces cain, right? But wouldn't it be better if he replaced "The Lost"? 'cus Lost gets one-shoted (exactly like sans), and the holy mantle that u can unlock for him would be the "miss", no? Maybe it's a lill' too much to ask.. :b

Anyway, great mod
It's giving me the mod in a .rar file, that i have no clue how unpackage.
To unpack rars use 7-zip or WinRAR
I Installed It But.Like When I Play Undyne Spears Dont Come Out Is That Just Me Or :PPPP

i can help even though i am not the creator:
Buy Afterbirth (but if you buied afterbirth and you are looking forward to buy AB+ install the AB+ version here:
how do i install it that it works????
je pense qui faut le DLC AB et si ta AB+ utilise se lien
June 5, 2018 - 1 year ago

The download button will now give additional details and link to a helpful announcement when you have not been verified as owning the game.