How to create mod installers

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What is a mod installer?

When used with a mod manager like Vortex, a mod installer (within the Bethesda communities often referred to as “FOMOD” installer) essentially adds an installation menu to a given mod, allowing users to e.g. choose from different options (for example a black or white version of an armour).

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What are the benefits of mod installers?

For users: added convenience

For the end user, mod installers such as the example above add the convenience of being able to choose which option(s) they want to install. Vortex will “remember” your mod installer choice even when you choose to disable a mod, meaning you won’t need to go through picking your options another time if you decide to enable the mod again.

To bring up the installation menu again, if - for example - you want to go with the white armour now, you need to reinstall the mod which will allow you to run through the installer and pick a different option.

For mod authors: one main file with all the options

For authors, mod installers mean that instead of having to upload and maintain multiple (main) files on a given mod page, for example, the black/white/red version of an armour, you can simply pack all options into a single file with an installer that allows users to pick the desired option upon installation.  

It is also noteworthy that without an installer, packing several options (e.g. all colour variants for an armour) into one file means users will have to pick manually since mod managers will simply default to moving all options into the games’ mods folder. This will lead to only one of the options being active, without the user being able to choose.


How do I go about writing a mod installer for my mod?

While it is possible to manually write mod installers, the process is made a lot easier by a community-created tool written by Wenderer. “The FOMOD Creation Tool” requires no previous knowledge of XML files, is not specific to Fallout 4, and can be used with other games just fine.

First, it is noteworthy to point out that the type of mod installer we are referring to is only a viable option for games with a designated “mod folder” where mod files need to be added in order to be recognised by the game.

Fortunately, many games follow this exact modding pattern. Note that the mod folder name might vary from game to game. Here are a few examples:

Game mod folder naming convention/path:

Most Bethesda games: Data/
Stardew Valley: mods/
Monster Hunter: World: NativePC/
Sekiro: mods/
Witcher 3: mods/
Kenshi: mods/
Subnautica: QMods/

If the game you are looking to mod is usually modded by having mods dropped into a destination folder, then the sort of mod installer described in this article is likely to work just fine.

A mod installer consists of two XML files: an “info.xml” and a “ModuleConfig.xml” both of which contain information Vortex will load during the installation process, e.g. in order to present users with various options.

Mod Installer creation: Step-by-step

Before we start, make sure that you have all the files for your mod together in one folder that you name after your mod and include any images (e.g. example images for various options) as well as a mod header image (the first image loaded in your mod installer).

Image Mod Folder

Next, download and unpack FOMOD Creation Tool to a destination of your choice and start it up.

At the bottom under “Workspace” click “Open” and select the folder containing all the files for your mod and answer “Yes” to the prompt asking whether you want to create a “fomod catalog”. 

Image Select Folder

Image No Fomod Create One

You can now fill in the mod information and select your Mod header image.

Image Mod Info Filled


Add an “Introduction” Step (Optional)

Many mod installers will have an introductory start screen that merely displays an image and says what the mod/mod installer is about. In order to create such a screen:

  1. Name your step (Step name) e.g. “Introduction” - this is the name that will be displayed in the installer.
  2. You can put anything as a group name - this is only referenced within the FOMOD creation tool.
  3. For “type” choose “SelectAll” - this will make this step into a preselected “option”. Since this step is not really about picking options (as it is just an introductory step), you want it to be preselected when the mod installer is loaded, which is what the “SelectAll” type will do.
  4. Click “Add” to add the group.
  5. On the right, put “Introduction” in the “Plugin name” field and click “Add” - this will add an option for this group (in this case, the only option).
  6. In the plugin description field, you can write up what the mod is about and what the installer will allow you to choose such as in the example.
  7. Select an image to display during this step for this option (we will simply be reusing the header image).

Image Introduction

Add Step with multiple options

If you have added an introductory step, simply click “New step” in the bottom right corner to add a second step. If you have not added an optional introductory step, this will be your first (and likely only) step.

  1. Name your step (Step name) e.g. “Pick your Outfit” - this is the name that will be displayed in the installer.
  2. You can put anything as a group name - this is only referenced within the FOMOD creation tool. In our example, we are calling the group “Outfit Options”.
  3. For “type” choose “SelectExactlyOne” - this will make it so users will have to select exactly one of the options, which is precisely what we want since the different options are mutually exclusive.
  4. Click “Add” to add/create the group.
  5. In the “Plugin name” field on the right, put the name of your first option (in our example it would be “Black”) for the black version of the armour and click “Add” - this will add an option for this group.
  6. You can add a description in the field that says “Plugin description”.
  7. Select an image to display during this step for this option. For our example, we will pick an image showing Sekiro wearing the black outfit to visualise this option.

Once you have done that, scroll to the bottom and click on “Add Folder” to set the folder you want to be extracted/installed for this option. Note: in our example, the folder structure for our mod is…

“Black Sekiro (and White)\Black\parts\”
“Black Sekiro (and White)\White\parts\”
“Black Sekiro (and White)\Black with Red Scarf\parts\”

We, therefore, want to select the folder “Black” as this will extract its contents (the respective “parts” folder with all the armour assets) when users pick the “Black” option. Image Correct Folders

We also want the respective “parts” folders containing the armour assets to be installed in “Sekiro\mods” which is the game’s mod folder. Because the FOMOD creation tool has been written for Fallout, the default destination folder is referred to as “DATA\” within the tool (as this is the mod folder name for most Bethesda games) - however, the installer will always default to the respective game’s mod folder. For Sekiro that will be “Sekiro\mods”. As this is the exact location we want our “parts” folder to be installed to, we can simply leave the field for the destination folder blank.


Repeat steps 5-8 for all of your options, selecting the respective images and source folders. In our example, we will be adding 3 options total: Image Option all except files


Once you have done that, go to “FOMOD > Save” in the top left corner. This will save your options to the info.xml and ModuleConfig.xml inside the newly created fomod folder.

And that’s it! If you want to make any changes to your installer, simply launch the tool again and go to “FOMOD > Open Folder” selecting your main mod folder containing the fomod folder.

All that is left to do now is to zip up your mod folder containing your mod files, the fomod folder, and the images (do not move the images to different folders or you will have to repoint them in the mod installer).

Upload your archive to your mod page and enable the “Download with mod manager” button (if you have previously disabled it, otherwise it will default to being active).

Users installing your mod with Vortex will now be greeted to a fancy new mod installation menu allowing them to simply pick the options they want without having to move folders manually: 

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Image Ingame

If you have any questions about how to create a mod installer for your mod, do not hesitate to contact one of our Community Mangers Pickysaurus or BigBizkit.