Modding is a very broad topic. This page serves as a portal to all modding-related pages on the wiki. Much information for this article is taken from the official User Modifications Reference — Guides, Templates and Utilities thread in the EU4 Paradox forums; check there for updates.
- Commands - Used in order to dynamically affect the game
- Conditions - Used in order to execute commands/events/decisions/etc. only when certain things are true
- Country list - Basic info on all countries in the vanilla game, including country tags
- Modifier list - Script modifiers that affect aspects of the game.
- Province ID map (warning: huge)
- Province list - Province IDs are used in many commands
- Scopes - Used to determine what entity commands and conditions are executed and checked from
- Variables - Persistent values that are either associated with a specific country or province.
Tools & utilities
- Clausewitz Maya Exporter - A tool allowing for easier creation of 3D models (units) to use in mods for newer Clausewitz games.
- Notepad++ Syntax Highlighter
- The Validator - Find errors quickly and with minimal pain! (Wiki Page: The Validator)
- Java Save Game Replayer
- Scenario Editor and Map Viewer
- Clausewitz EU4 GUI Mod Editor
- JoroDox mod making tool (wiki page: JoroDox mod making tool)
- EU4 Province Color Picker
- CW Tools for VS Code - Provides interactive validation as well as features such as completion, localisation generation and hover info while you write
- If you use Microsoft Windows, consider using Notepad++. Standard Notepad is considerably unreliable when it comes to respecting structure and format, and can bring a bunch of unnecessary headaches.
- If you use a GNU/Linux distribution, almost any text editor will respect structure and format. Examples of free text editors (or IDEs) that will respect structure and format include gedit, Geany, Atom, Vim, nano and Emacs.
- If you use Microsoft Windows, make sure your Europa Universalis IV folder is automatically indexed by Windows (right-click on folder, Properties, Advanced Options), so that, when you search within it, the function can search within text files. When you first enable the setting, you'll have to wait a bit for Windows to do the indexing in the background. (Alternatively, just use Notepad++'s "Find in Files" functionality, which is a lot better than Windows at searching.)
- When trying to find a way to do something, look around the game's structure to see how the game accomplishes similar things. The previous point helps with that (how is X effect/trigger meant to be used?). It's also a useful technique to learn about proper format, how events, decisions and missions work, and how to balance your changes with the rest of the game.
- Uncommon/unknown file types outside the gfx folder (i.e. .lua, .gfx, .gui) are usually normal text files, and can be opened as such.
- Read the Modding section!
- Save the List of Effects, Modifiers, Scopes, Triggers, and Localization Strings to a text file(s) for easy access. It's a quick reference to all the gears that make EU4 tick, and there's sometimes usage tips to be found.
- If all else fails, drop us a question here in the Quick questions thread over at the official EU4 modding forum.
- If you use Windows and want to merge mods, you could use WinMerge, an easy tool for merging folders and files.
- To upload a thumbnail with your mod, you must call it "thumbnail.png", it must be 512 x 512 or lower, it must be placed directly in the folder of your mod, and the line 'picture="thumbnail.png"' should be added to the second line of the descriptor.