Modding, or creating mods, is the act of modifying the game files in order to cause changes or create new behavior within the game. There's a lot that can be done with modding - this page seeks to be a clear outline of what modding is, what you can and cannot mod, and other important high-level concepts.
If you're looking for installing mods, check that page.
And you can check the modding tutorials page for a portal about various available, specific tutorials.
What's a Mod
A mod - short for "Modification" - can be anything user-created that edits the game in a meaningful way.
In the Total War series, mods are composed of a single file - a .pack file - which contain all of the changes within that mod. Packs act like a .zip or .rar file, a compressed folder in a single file. Much of the vanilla game is composed of various CA-made pack files.
Packs can contain a lot of various pieces, such as:
- Data: One of the most-used parts of a mod is databasing. Total War uses database files, similar to spreadsheets, which can be used to change behavior and values, or add new objects to the game. This is used for much of the game, from units and their stats to the cost of buildings and much in between.
- Text: On top of that, text you see in the game - from the name of a lord to the flavour text of a skill - is done within packs, in .loc files. These files attach text to the database, and they can be used for translations as well!
- Assets: This is a wide topic - but much of the game can be edited through assets. Assets range from .png images scattered throughout the UI, to altered .dds files which are used on the various unit models in the game, to entirely new models or otherwise.
- Battle Maps: Battle maps are created through the Terry tool, from within the Assembly Kit.
- Scripts: There's a layer of the game that can be interacted with through scripts (.lua files). Scripts power things such as characters getting experience, legendary lord defeat traits, and the Chaos Invasion - and much in between!
There's natural limitations to modding the game, since the game is written in a way that cannot be decompiled easily - meaning much of the game code and engine is unreadable and untouchable. That said, Creative Assembly does a comparatively excellent job at making sure much of the game is exposed to being modified!
You've decided on a general mod idea you want to do, and you're ready to set aside some time to try, fail, try, fail, try and then inexplicably succeed the third time. This is the spot for you!
First thing's first, before you go on, you need to grab the Rusted Pack File Manager, by Frodo. It's the primary tool available to create a .pack file, edit it, and manipulate it in whatever way, and comes with a lot of excellent functionality.
Right after installing RPFM, you should decide on a folder on your computer that you'll store your mods. This'll be your primary directory for modding. For instance, I have S:/modding/ determined as my main spot on disk. Name it whatever you want, put it wherever you want.
Then, within RPFM, open the Preferences menu (through Ctrl+P, or PackFile -> Preferences), and begin to set up the necessary preferences within. Target all of the folders for all installed Total War games, targeting the folder where the .exe of the game is. Underneath, in "MyMod's Folder", fill in your new folder.
Fill out whatever other preferences you may like, but most of this stuff you'll see through time. Keep "Allow Editing of CA PackFiles" to false, I prefer to have all of the checks valid on start, and of course the Use Dark Theme setting is an absolute must.
With RPFM, we can do an absolute load of modding. I recommend using GitHub for version and source control - it's saved me several dozen times when I almost certainly would've lost an entire mod, or gotten two versions (ie. an update version and the retail version) mixed up.
With all of our tools set up, we can get started on our first mod!
This is a list of hopefully helpful tips for modders - new or old.
- Start small, build up. One of the oldest tricks in the book is having a tremendously bloated idea, trying to make it all at once, getting overwhelmed, and then quitting. We've literally all done it. Instead of trying to build a pyramid from the bottom up, try to build a glacier from the top down, starting with a simpler idea and continuing it naturally.
- Ask for help. The Total War modding community, especially that around the Modding Den Discord, is a big help - you're not in this alone.