ULTRAKILL MODDING KIT - Basic Guide

ULTRAKILL Modding Kit is a unity project i've made for easier access to model replacement, and audio replacement. This kit offers weapon prefabs, props, and enemies that you can modify to what you desired. This guide will explain all technical details of the kit and how to use it.

Getting Started

Without long explanation I'll be giving some information on what files are you able to replace.

List of Replacements (Confirmed)

Weapons are easy to replace (see Model Replacement section)
Textures2D/Textures/User Interface (See Replacing Vanilla Content Using UABE)
Audioclips (see Custom Sounds / Custom Music For Cybergrind)

REQUIREMENTS

•Unity Asset Bundle Extractor[github.com]
•Unity Version 2019.4.16f1
•Autodesk Maya (For Weapon Replacement & Character Replacement*)

I did not put Blender in the list because blender has major flaw that if you export the file then model transform will be error on unity
this because blender has different way to export model along with their transform. The only way to do this is using Autodesk Maya (Yes, good luck on that)

Installing The Project

Download the kit from Nexusmod [www.nexusmods.com] then extract the content & download Unity Version 2019.4.16f1. Other version won't work because the game use said unity version (don't forget to install unity hub). Next thing you need to do is launch the kit using unity by opening unity hub, then click Add and select "ULTRAMOD" folder. Voila you're now in the kit.

Overview

Opening the project you can see lots of folders starting from CORE to Vanilla. CORE contains all data from the game itself, I would not advice to touch anything inside the folder.

Modded is folder that contains all your modded file and scenes that contain modded file.
Scenes is folder that contains all character, weapons, and several props that you can use to test the modded file.
Vanilla is where all meshes stored.

MAYA METHOD - Replacing Vanilla Model

To replace the model what you needed to do is to navigate through the scene. For example lets say i'm trying to replace Railgun model with Dubstep Gun from Saints Row 4. What I need to do first is to create new scene and save it to Assets/modded/scenes/ (if you don't have the folder create one). Next lets drag the model from vanilla folder, go to Assets/vanilla/weapons/railgun/.


Now go to hierarchy tab and select dropdown of Railgun, here we need to replaceRailgun_Main_Low mesh to custom one. Now open Autodesk Maya and import fbx file of railgun (file > import...> railgun.fbx > import). We also need to import Dubstep Gun



Once we have the vanilla railgun imported we need to import our custom model, It's the same step where you need to import (file > import...> your custom model here > import). If the model have scale difference or different location you can manually adjust the model using move tool and drag tool.



Before we start rigging the model, be sure that the original model must be unbind skin or else when you try to rig the modded model it will show an error and the custom model must be inside Railgun hierarchy so the program can bind the skin.


Next we need to bind the modded skin to Railgun armature/bone. Go to Menu set menu (top left that has modelling/rigging/animation option) then click rigging, after that select skin menu then bind skin, be sure that your custom model and its original bone has been selected. in Bind Skin Options pick bind to : selected joints then click apply and bind skin. You have now your successfully rigged your model, export the model as fbx and put it to assets/modded/weapons/ then we can proceed to the next step.

Replacing The on Unity

Now go back to unity project and select Railgun_Main_Low. Go to right window and you can see inspector window, here you need to click mesh in skinned mesh renderer. But first we need to highlight the custom model first so go to assets/modded/weapons/ and click your custom model (mine called dub.fbx). Click dropdown funny arrow and there is some information we can see, for example there is materials inside the model or animation or even mesh. Now we don't need to drag the model to the scene, we just need to drag the mesh inside dub.fbx (mine is Railgun_Main_Low.001).



Now lets get back to railgun and go to skinned mesh renderer option again, here we need to drag Railgun_Main_Low.001 to replace Railgun_Main_Low. Congratulations you just replace the model with Dubstep Gun. Don't forget to save the scene

BLENDER ONLY - Replacing Vanilla Model

If you are uncomfortable with replacing the model using Maya, then you can try replace the model using blender. To do this you need to download Fixed Weapon Transform[www.nexusmods.com] this package containing models that has been adjusted its transform.

Once you have download the file you can import one of you liking, let say we're gonna replace alt revolver so lets open blend file of revolver.blend. Keep in mind every weapon has different transform, if you decided to use this to replace default pistol model then it will break the original transform.

Be sure that the original model of the altrevolver has no armature modifier and save the blend file in another name, lets say magnum.blend. Good we're halfway there, now import the modded weapon to magnum.blend. If you check your custom weapon object properties it might be in another transform, we need to click alt + a > all transform. The reason to do this is we need to make sure the custom model is in 0 location, 0 rotation, and 1 scale while the vanilla model scale has different one we need to make it the same. Mine vanilla alt revolver scale is 39 39 39 so we need to set this to my custom model.


Once you have done that press tab or go to edit mode and scale it down to fit with the vanilla model that does not have armature modifier. Next we need to adjust its location and rotation through edit mode only. Press R twice to rotate the model or Press G to move the model around. Now you might be wondering, why don't we do this in object mode? well changing the transform in object mode would create flaws within the final result. If you happy with the final result then lets go to rigging part.

Rigging The Weapon

To rig the weapon, we need to add armature modifier to our custom model so go to modifier properties > add modifier > armature and select "armature" (DO NOT PRESS APPLY MODIFIER). Next select the armature bone and select the custom model too then go weight mode (top left it said object mode , you need to click it to weight mode). Now select the individual bone name "bone" then change the brush from "draw" to "add". Left click your mouse to paint the weight on the custom model, make sure you fully paint all the area or else the vertex would go stretch due to unpainted weight.




Once it is finished it would looked like this:


Lets save the file, go to File > Export > FBX (.fbx) > name your model > export FBX . You don't need to make changes around the presets/setting so just leave it default. Congratulations you are able to rig the model in blender.

Building & Saving Your Mod

To make your custom model usable in ULTRAKILL you need to build the mod first. Go to file > build setting and click "add open scene" be sure the scene you add ONLY containing modded file. After that click build and voila, the file has been built.

Next step is to extract raw file from .asset where you save your build. Open Asset Bundle Extractor and go to file > open and navigate through your ULTRAMOD_Data and select sharedassets0.asset. What we want to extract is a mesh file type correspond to the name of the mesh in unity, mine is Railgun_Main_Low.001 so lets export the model. Click export raw and save your raw in your desired location.

Now we open another Asset Bundle Extractor, the reason is for easier navigation. Now lets open assets folder click file > open and go to ...\Steam\steamapps\common\ULTRAKILL\ULTRAKILL_Data and select sharedassets1.assets and then lets open common file by click file > open and go to ...\Steam\steamapps\common\ULTRAKILL\ULTRAKILL_Data\StreamingAssets and select common.

This is where the fun begins, to find the mesh inside this clutter of information we need to find the original mesh name of the railgun. Now if you see the railgun name in unity the model name is Railgun_Main_Low (applied to sharedassets only) so lets find this by sorting the assets by clicking type, go to Mesh type section and select Railgun_Main_Low. Here we need to click "Import Raw" and go to your exported Raw directory and select that raw. Be 100% sure that you are clicking the correct .dat file, incorrect file will result in game crash. Now you have replace the model with custom one, but hold on the texture is still jimbly jambly how can I fix that? well we need to go to unity project again and click on Railgun_Main_Low. At skinned mesh renderer you can see there is materials tab than contain original material of the railgun. Scroll down on inspector tab and we can also see material name (mine is Railcannon unlit) so lets select Base texture and we can see name of the texture, it is Railgun_Main_AlphaGlow so lets to go Asset bundle Extractor again and click View > Search by Name and input Railgun_Main_AlphaGlow. Once the tool found the texture lets replace the texture with modded texture so click on plugins and press edit. Load the new texture and navigate through your modded model & texture directory and select the texture.


After done modding sharedassets1 bundle, Lets go to common bundle. In common bundle we can try the same way we search railgun model but instead of Railgun_Main_Low, the asset will be name Raingun.fbx. So lets click sort by type and also click sort by name. Here we need to find Railgun.fbx, once you found it click import raw and go to your exported Raw directory and select the modded raw. Once you are satisfied lets replace the texture. Click on container and here we only need to find the texture in assets/models/railcannon/ container. Once you found Railgun_Main_AlphaGlow.tga replace it by going to plugins > edit > load texture. Congratulation you just successfully mod ULTRAKILL. Save the file in your desired location and be sure to make backup of common and sharedassets1.asset file.

Exporting/Installing The Mod

To prevent complicated install by replacing this and that you can try creating executable installer that contains the mod only. To do that open Asset Bundle Extractor and go to File > Mod Maker > Create Standalone .exe installer. Put any description and mod name you like but you need to select a base folder to ...\Steam\steamapps\common\ULTRAKILL\ULTRAKILL_Data\ and click OK. You're done.

Closing

And you're done, that's basically how to use ULTRAKILL Modding Kit. This kit is intended for model replacement purpose or audio replacement purpose. If you have any question or issue please comment down below

FAQ

Q: How long did you figure this out?
A: 4 or 5 months? The reason why it takes so long is Asset Bundle Extractor at the time does not support open common files so thats a bit bummer until they released new update that lets you open common files.

Q: How did you manage to repack the whole thing again?
A: I use certain tools to decompile the file into unity asset and once I have all the things I needed, I import them back to unity project. However the file is so messed up I need to tidy things up and be sure it is working as inteded.

Q: Why can't I use blender instead of Maya? It's infruriating to use
A: The reason why Maya is needed to use is because Blender has a different way to export fbx file. For example if you export the model that lets say is in Y axis then in Unity it will rotates to 180 degree while Maya export fbx file as the same transform as Unity. So good luck on using Maya, you need it.

Q: Can you replace character model?
A: Yes and no, the only character model that did not bugged out when replace is virtue, drone, idols, and malicious face. Others might encounter issue such as streched vertex due to different mesh or different setting.

Q: Can you mod audioclips in this project
A: Yes definitely, you can mod audioclips inside this project

[Froggy]

Railgun_Main_Low.001 doesnt show up for me in the modding kit's sharedasset, did i save the build incorrectly?

[GGamer]

Can you edit text with this one?

[crazy jhead]

is it possible to redo animations with sfm or no, does that require the game to be ported into the source engine?

[Lotr1k]

Btw if anyone has experience with the replacement model please write me, I would be very grateful.

[Lotr1k]

I don't know if the guide is still working, but I decided to replace the model rail gun using the blender method and I can't find the common folder.

[Pirangunter21]

@deMONSTRator I haven't test this method but you can just rig the PNG model into the "root" bone of the vanilla model remove delete the vanilla model

[deMONSTRator]

Hello, if i want to change Filth model with PNG (like nextbot) is there an easier way to do that? Or can i make what i want with your method (preferably with blender)?

[Pirangunter21]

as for arm models, yes

[Seven4941]

Blender won't do even with the fix thing from nexus?

[Pirangunter21]

it's possible but you need to use Maya so the rig won't be a problem in the game