Asset Basics

About Assets

This article summarises some basic knowledge about assets.

Mods (and the game data of the vanilla game) consists of two basic file types: Plugins and assets.

Asset Types

All asset types must be located in the data folder in a top-level folder of the same name (i.e., \Skyrim Special Edition\Data\Textures\). The following file types are recognised by the game:

• Textures (.DDS)
• Meshes (.NIF)
• Scripts (.PEX)
• Animations (.HKX)
• Interface (.SWF)
• SKSE\Plugin (.DLL)
• Sound\Voice (.FUZ)
• Sound\FX (.WAV)
• Music (.XWM)

*The list is not 100% complete, but these are the important ones.*

Different asset types handle very differently from each other (unlike plugins) and more time is required to learn how to substantially modify them. On the other hand, sound design, 3D modelling, etc, are (again, unlike plugins) widely applicable skills and not unique to Bethesda’s Creation Engine.

Generally speaking, you do not need to become as adept at modifying different types of assets as you do at modifying plugins in order to build a solid setup.

Bethesda Softworks Archives

Assets can be present in two forms: as loose files or BSA-packed. Loose files always overwrite packed assets.

Bethesda Softworks Archives (BSA) are essentially 7ZIP or WinRAR archives for Creation Engine assets. All vanilla assets are packed into the 17 BSAs in the data folder which are compressed to save space. Many mods are also published with their assets packed into a BSA.

BSA Types

There are two types of BSAs:

• Example.bsa
• Example - Textures.bsa

Obviously, the latter type is intended specifically for textures. Use the regular type for all other kinds of assets.

BSAs can be compressed or uncompressed. Looking at the vanilla BSAs, you will notice that archives containing textures and meshes are compressed while all others are uncompressed. I recommend mirroring this logic when creating new BSAs.

Loading BSAs

A BSA always requires a plugin with the same name to be loaded.

Example.esp (or ESL/ESM) can load Example.bsa and Example - Textures.bsa, but no more than that. If the name does not match exactly the BSA will not be loaded. The plugin does not need to have any content, it can be an empty ‘dummy’ (in which case it should ideally be an ESP-FE).

Manipulating BSAs

You can preview BSAs through Mod Organizer 2 or with Bethesda Archive Extractor. Different ways of extracting BSAs are described here while creating a Cathedral Assets Optimizer profile for re-packing BSAs is detailed here.

Mod Order

Similar to how plugins overwrite each other according to their placement in the load order, so do assets overwrite each other according to their placement in the mod order.

The mod order is a concept created by Mod Organizer 2 and its virtual data folder which prevents assets from irrevocably overwriting and replacing each other by placing them in separate folders.

BSAs & Load Order

As a consequence of being attached to plugins, BSAs adhere to load order rather than mod order. This means assets packed into BSAs overwrite each other in the order of their plugins.

It makes sense to BSA-pack assets from mods that serve as a baseline intended to be overwritten. On the flipside, assets from mods that should generally overwrite are best kept as loose files.

You may also want to extract an archive in order to be able to compare its assets to other assets in your mod order. NifSkope, for example, can only load loose textures and meshes, not BSA-packed ones.

Archives & Plugins

If you have two archives or plugins with the same name, the one from the mod lower in the load order will overwrite and replace the other. BSAs and ESPs/ESMs/ESLs are essentially a type of asset as well and adhere to the mod order.