How to mod Undertale's Sprites!

This guide will teach you how to make custom sprites, and import them into the game!

Starting Things

1: Search Github for Undertale Modding Tool. Let that download.
2: Boot up the tool and unzip it. Remember to verify those files so the software works properly.
3: Go to Files and then Open. Go to your Undertale main folder. Select it's data.win file. Wait for UTMT to load the game data.
4. Go up to Scripts. Go down to Resource Unpackers. Look through the list till you see ExportAllSprites.cxs. If it asks anything, just say no.
5: After the sprites are done exporting, look at your game folder. there will be a new folder titled Export_Sprites containing every single sprite in the game. You'll be working with these.

Making Custom Sprites

1: I recommend buying Aseprite from the steam marketplace, or buying it's trial version Libresprite, from their website.
2: Open up the software you are using. Open a file, and go to the Export_Sprites folder. If you are doing a player mod, search mainchara in the searchbar. if you are going for other characters, like Sans or Toriel, search their names lowercase.
3: Open the desired file. If you are using Aseprite or Libresprite, it'll ask you if you want the files selected bundled as a gif. If you are using the frisk walk cycles, press ok.
4: Edit the sprite to your hearts content and save.

Importing them in-game.

1: Go to your undertale folder. Create a new folder called Sprites inside. This is where your sprites will go.
2: Make sure your sprites are saved in this folder as a .png file! Gif or jpeg (ect) will not work!
3: if you have all needed sprites, go back to UTMT. Go to Scripts, Resource Repackers, and then click ImportGraphics.cxs
4: Click okay on the popup. feel free to read.
5: when it brings up the file selector, go to your Sprites folder from earlier, and click it once then click okay.
6: Once it says "Import Complete!", press the okay button. Go to file, save, then save the modded data.win to a new location. you can now quit out of the program.
5: Go to File explorer, (location with modded data.win), copy the data.win file, go to your undertale, then delete the pre-existing one in the game folder. Now paste the Modded data.win into the game folder. Close file explorer once the file is safely inside the game folder, and go back to steam
6: Open undertale.





And wherever you put your custom sprites, they should show up in-game!

[NameInUse]

ok thx but can u make a steam deck tutoriel?

[LukeTheSoupYT]

@Nc-SkyRiMer They won't be cut off, but will appear MUCH bigger than other sprites.

[Dainrun]

щас чекну, а вопрос заранее, можно сделать спрайт чуть больше чем у Фриск? Он обрежется?

[ManicEraser0912]

You don't realize what you've done, now more people can make Jerry look like Senator Armstrong. ... ... ... ono

[Aerom]

Thank you! Now I can start work on my Bug Fables mod of Undertale!