Tips to install a mod for Fallout: New Vegas

Anybody who plays Fallout: New Vegas on a PC has at some point come across a mod for it that makes them drool and wish the vanilla game already came like that.

Tips to install a mod for Fallout: New Vegas

Mods can seriously enhance a game by fixing bugs or implementing ideas that make the experience more enjoyable, but they are often a bit intimidating to those who are a little uncomfortable mucking about with the internal workings of their game.

What is a Mod?

Not to be confused with scooter-riding young people in 1960s Britain, a mod in the computer gaming world is a game modification. They are often created by end-users on an amateur basis, and can be applied to a computer game to add items, alter gameplay or even completely convert the game into something else, in effect creating a whole new product.

If you’re reading this article then you probably already have some idea of what a mod is, but for clarity: most mods for Fallout: New Vegas either add items in the form of texture and mesh files and then place these in the game somewhere, or alter the gameplay mechanics by adding a file that tells the game to behave a little differently than it would without the file installed. Clicking on the Data Files option of the startup screen lets you view which mods are installed, if any.

In general, mods never alter the base files of the game and, while incompatible Fallout: New Vegas mods may conflict and cause your game to crash or behave funnily, they will never render the game so far inoperable that simply reinstalling won’t solve it.
The big exception to this is, of course, body replacers. These can actually replace the default textures (skins) of game characters with something else and, for this reason it is always, always advised to backup your original mesh and texture folders. A problem with a texture replacement will not cause your game to crash, but it can result in some goofy looking people wandering the Strip.

Data Folder

So, where do we find these texture and mesh folders?

Fallout New Vegas

This brings us to one of the most important things to know about Fallout mods, the data folder. This folder can be found in your Fallout: New Vegas directory, the place on your PC that the installer put the game and all its files.

This will generally look something like:

C:\Program Files (x86)\Bethesda Softworks\Fallout New Vegas,
or C:\Program Files\Steam\steamapps\common\Fallout New Vegas, with Steam.
This data folder contains the files that the game looks at before starting up to know what it will contain and how it will behave.

For most simple mods installing is as simple as copying the files in the mod’s folder to this data folder, merging when asked and sometimes overwriting. These mod folders often need to be unpacked with 7-Zip or a similar program, but that’s really as complicated as it gets.

Often, the only file in the mod’s folder is an .esp file, this is the file that tells the game what to change and is the file that will show up to be activated in the game’s launcher. Once this is done you can launch the game, select the Data Files option and put a tick next to the mod you just installed, hit ok and then play to reap the benefits of your new and shinily installed mod.


You may have come across a mod or two that doesn’t have these .esp files to drop into the game’s data folder, instead being presented in what is known as FOMoD format. This is a format designed to work with the excellent Fallout Mod Manager (FOMM) that can be found on the site: . The Mod Manager does the same job as the Data Files option in the Fallout: New Vegas launch screen, just a hell of a lot better. Mods in this format are more stable, can be customized more easily and are generally flashier.

Once you have FOMM installed, launch it and you will see something very similar to the window in the Data Files screen. Normal .esp mods can be clicked and activated here in exactly the same way as you may be used to. To install an FOMoD however, you will need to click the Package Manager button. This will open a new window from which you can select Add FOMod and then choose the mod file you have just downloaded to add it to the list. Select the mod, click Activate and simply follow the instructions, if any, to get your new mod up and running.

Archive Invalidation

Tips to install a mod

One final thing you need to know is a particularly confusing little file called Archive Invalidation. When you replace something in the game, such as the player character’s body textures, the game needs to be told that its archive of what it contains is now wrong and should be altered to include the new files.

This is where ArchiveInvalidation.txt comes in, and most mods that require it will include their own version of the file as well as specific instructions as to what needs to be done.

For simplicity’s sake, downloading a helper such as Archive Invalidation Invalidated is probably the best way to go. There is some poking about in the Fallout_default.ini file during installation, but once this is done and the instructions on the page are followed you can say goodbye to worrying about Archive Invalidation for good, in theory at least.

For FOMM users, the Tools dropdown menu in the main window lets you toggle Archive Invalidation on or off, which can be very handy when textures don’t seem to be installing how they should.

That just about covers the basics of installing mods for Fallout: New Vegas, although as there are so many mods out there something unexpected is bound to crop up. The best advice is to carefully read the mod’s description as well as the Readme file included, the author put it there for a reason.

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