Undertale Connect
A downloadable mod
UNDERTALE CONNECT is an online multiplayer mod for Toby Fox's UNDERTALE. With up to 10 players, you can explore the UNDERGROUND together without having to destroy anyone.
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GALLERY
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CREDITS
Landimizer - Programmer
Luigi (UTMC) - Programming assistance
RedstoneRuler - v1.08 input delay fix (Included with v1.2 and v1.3)
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Download
Install instructions
Method 1 (Recommended)
Undertale Mod Manager
https://gamejolt.com/games/modmanager/896341
1.) Download Undertale Mod Manager, extract the .zip, and open UT Mod Manager.exe
2.) Select "Add Game" and point it to your UNDERTALE (v1.08) directory
3.) Select "Add Mod" and point it to the Undertale Connect .zip file
4.) Select the mod and hit "Play"
Method 2
DeltaPatcher
https://github.com/marco-calautti/DeltaPatcher
1.) Download DeltaPatcher and open DeltaPatcher.exe
2.) Click on the folder icon next to "Original file:" and select Undertale's data․win
3.) Click on the folder icon next to "XDelta patch:" and select the .xdelta file included in the Undertale Connect .zip
4.) Click "Apply patch" and wait for the confirmation window
5.) Transfer all files from the .zip to your Undertale directory and replace as needed
6.) Launch UNDERTALE.exe
Port 6666 will need to be forwarded to host a server.
Development log
- v1.3.3 released51 days ago
- v1.3.2 released62 days ago
- v1.3.1-hotfix released81 days ago
- v1.3.1 released82 days ago
- v1.3 released + Trailer & Discord89 days ago
- v1.2-hotfix releasedApr 27, 2025
Comments
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it's not working
really good works, thank you for this mod!
Seeing as nobody is getting replies here nor on any of the other mod pages/youtube I doubt I will get a response but... How to make the skins work?
I download the mod, go to configure/settings and there I am able to change my soul colour.. however when I go to change the skin and pick my or the example zip file, all it does is reset it to the original skin + default soul colour.
So what am I supposed to do? I cannot find anything about this anywhere
hit me on discord i'll u : sakoushi
Black screen and wind sound when trying to host?
How do you save? It says I cannot save my game.
Is it compatible on mobile?
obv no undertale is a desktop game
no because 1, the mod is local online thus anyone you want to play with needs port forwarding, 2 undertale is a paid game and thus porting this to a phone would be illegal.
how do i put a custom skin, i made one from urotsuki and in the game it´s just frisk
Is it all sharing the same savefile. Or is it mario wonderesque where people just happen to be fighting the same enemy but it doesn’t really affect much outside of that. Is there a way tk share health
for some reason it won't download because it says there was a virus detected, is there a way to download it anyway or no?
i use Windows and am on Google Chrome
Go to your security settings on Chrome, or use a different browser. I was able to download it fine on Firefox. When unzipping the file, Windows Defender may try to remove it so make sure you tell it to keep the file.
i have save data and its not working could this be the reason and how do i go about making it work because it justopens up undertale the main game
Is trojan?
No, it's just windows being stupid. Recent-ish update started marking a lot of third party utilities (usually made with the intention of turning games into multiplayer, like this one here) as 'trojans' (Despite not being trojans.)
Research, don't just go right to assuming Windows is correct 100% of the time. :)
Esta bien, pero no tengo amigos con quien jugarlo D:
the comments makes me not want to play bye
im confused on how to join people
it probably works but noones ever playing sadly
I tried to download it, but never started :(
Can you do something to teach us how does this even work, like what to do to connect 2 different pcs? how to host a servers, what to write, anything?
gotta love
___________________________________________
############################################################################################
FATAL ERROR in
action number 1
of PreCreate Event
for object obj_network:
trying to index a variable which is not an array
at gml_Script_scr_murderlv
############################################################################################
worked till this happened
___________________________________________
############################################################################################
ERROR in
action number 1
of Async Event: Networking
for object obj_network:
Attempting to read from outside the buffer, returning 0
at gml_Object_obj_network_Other_68
############################################################################################\
i use hamachi
got that error while flowey in the second room
how to use this mod
install utdr mod manger import it dont unzip it play make a server nobody is making servers
how tf you use it