Modding

Version

This article is considered accurate for the current version (2.5) of the game.

Modding, or creating mods, is the act of modifying the behavior of the base game (often referred to as vanilla), either for personal use, or to release publicly to other players, for instance via the Steam Workshop.

As for all Paradox games, Stellaris is moddable to a great extent. Motivations of modders may vary widely; better translation to native language, more events or decisions, better map, major overhaul, shameless cheating, etc.

This guide is intended to lower the entry barriers to the world of Stellaris modding. However, there is still a learning curve to it, and it cannot replace the need to read some working vanilla code, and do lots of trial and error experimentation!

Modding

Guidelines

• Create a mod for your modifications: use a personal mod even for small changes, and never directly modify the game files in the Steam Stellaris folder, as they may be overwritten without warning.
• Use a good text editor (recommended: Visual Studio Code) to edit files and search into multiple files. A good text editor can also format the displayed text so that braces can be collapsed if complete, and complete/incomplete pairs are highlighted.
• Use the Error.log file to get execution errors: The log folder can be found right next to the mod folder. Good Editors usually have the ability to track changes to files from outside the program and prompt for a reload, thus showing you errors with one glance at the file. Note that some modifications need a game to be loaded or even the option to be used on screen/in the back-end before their code will run.
• Use CWTools for advanced validation and auto-complete: CWTools is a syntax validator for Stellaris modding, developed as an extension for Visual Studio Code and also available for Sublime. Read the forum post by the developer for more info.
• Minimize overwrites of vanilla files, unless that is your main goal or somehow necessary (on_action triggers). Adding separate files and use loading from folders whenever possible, to improve mod compatibility and maintenance. Your files can have any name, all files in the folder will be loaded by the game. So choose a prefix no one else will ever use like the name of your mod. Even DLC follows that pattern.
• Use a proper merge tool (like WinMerge), to merge between folders, and update modified vanilla files to a new vanilla patch.
• Backup your work to avoid losing everything. Consider using a source control system like Git and a collaborative forge like GitHub to manage team collaboration.
• Use UTF-8 encoding for text files.
• Use UTF-8 with BOM for localization, name list, and .mod files.
• Indent properly and, again, use a good text editor, to easily spot unclosed curly braces. Vanilla uses 1 tab for indentation rather than spaces.
• Use comments starting with a # character, to remember your reasons for writing tricky stuff.

Mod management

The first steps of modding is getting to know where the mods are located, how they're structured and what to do when uploading your first mod!

Mod folder location

OS	Path
Linux	~/.local/share/Paradox Interactive/Stellaris/mod
Windows	C:\Users\<Username>\Documents\Paradox Interactive\Stellaris\mod
Mac OS	~/Documents/Paradox Interactive/Stellaris/mod

Mods from the Steam Workshop will be placed in ...\SteamLibrary\SteamApps\workshop\content\281990, sorted by their Workshop ID.
Mods from Paradox Mods will be placed in the mod folder location, named PDX_*MOD_ID*.

File and folder structure

Getting the structure set up correctly when creating a mod is essential for it to run properly.

This is the required structure inside the main mod folder:

• modname.mod - Includes the information used by the Stellaris launcher
• modname - Folder where all the modified files are placed, in the same file and folder structure as the game folder
  • Mod contents
  • descriptor.mod - Required for the new launcher added in patch 2.4
  • thumbnail.png - Must be named thumbnail, only PNG files supported

modname.mod and descriptor.mod both contain the mod information that the launcher uses when displaying the mod and uploading it.
These files are best kept identical to prevent any missing data.
Note that folder and file names are case sensitive on Mac OS X and Linux.

modname.mod structure
This also applies to descriptor.mod.

Name	Required	Description	Example
name	Yes	Name of your mod.	name="My Stellaris Mod"
path	Yes	Defines which folder is the mod's folder. It is relative to ...\Documents\Paradox Interactive\Stellaris\ folder.	path="mod/MyStellarisMod"
dependencies	No	Specifies if the mod should be loaded after the listed mod(s), if they exist. Very useful for submods or compatibility patches to make sure they overrule certain mods.	dependencies={ "My Other Stellaris Mod" "Not My Stellaris Mod" }
picture	No	Specifies the mod thumbnail used on Steam Workshop. Must be a PNG file.	picture="thumbnail.png"
tags	No	List of tags for Steam Workshop. Warning: don't forget quotes for tags that contain spaces.	tags={ "Tag1" "Tag2" }
supported_version	Recommended	Specifies what game version the mod supports. The last number can be replaced with the asterisk (*) symbol to tell the launcher that mod supports any value, like 2.4.*. Only the last number supports this.	supported_version="2.4.1"
remote_file_id	No	Property added by the launcher that includes the Steam Workshop ID. Ignore it.	remote_file_id="1234567890"

Example modname.mod file:

name="Somemod"
path="mod/somemod"
dependencies={
	"othermod"
	"another mod"
}
tags={
	"Graphics"
	"Economy"
	"Overhaul"
}
picture="thumbnail.png"
remote_file_id="1234567890"
supported_version="2.4.*"

Adding a thumbnail

The Steam Workshop allows for a preview thumbnail picture that'll be displayed when searching for mods and as a preview picture if you haven't uploaded any, otherwise it'll be placed to the right of the preview pictures.
It's recommended to make the thumbnail 512px × 512px at minimum, which is used by the workshop frontpage.
Additionally, the thumbnail file should be under 1 MB in size, otherwise, it will not be uploaded.
Both JPEG and PNG are supported, and after 2.4, the image file must be named thumbnail.

1. Make sure the Stellaris launcher is closed, so that it doesn't revert your changes
2. Open up modname.mod and descriptor.mod files
3. Make sure picture="thumbnail.jpg" exists, if not, add it
4. Add your image file in your mod folder
5. Start up the launcher and update your mod
6. Thumbnail should now show up at the Steam Workshop mod page

You can always update the thumbnail at any time by updating the mod.

Creating a mod

You can use the game launcher to set up a the mod structure for you by following these simple steps according to your launcher of choice:

#	Launcher v1 (<=2.3.3)	Launcher v2 (>=2.4.0)
1	Launch the game
2	Navigate to the mods tab
3	Click Mod Tools
4	Click Create Mod
5	Insert the relevant information and click Create Mod at the bottom
6	Navigate to the mod folder and locate your mod folder
7	Start modding!

Uploading and updating a mod

Uploading and updating a mod follows the the same procedure, depending on your launcher of choice:

* - The inserted description will replace the current one used on the mod page!

#	Launcher v1 (<=2.3.3)	Launcher v2 (>=2.4.0)
1	Launch the game
2	Navigate to the mods tab
3	Click Mod Tools
4	Click Upload Mod	Click Upload a Mod
5	Select your mod from the list
6	Click Fetch Info and wait for a response	Select mod site
7		Insert description*
8	Click Upload	Click Upload Mod
9	The launcher will now upload your changes and inform you when it's done or if an error occurred.
10	Navigate to the mod service of choice and locate your mod; Steam Workshop, visit the Workshop page, and locate the "Files you've posted" button by hovering over "Your Files" on the right Paradox Mods, visit the Mods page, login, and click "My uploaded mods" in the dropdown menu that appears when hovering over your name

Game data

• Console commands, useful for debugging mods.
• Defines, which allows you to influence some hardcoded vanilla behaviors
• Scopes, Conditions, and Commands used for scripting
• Modifiers, used to influence calculations made by the game
• Events, used to define popups with decisions
• Map, used for pre-generated galaxy maps

Game structure

Below is a list of game files and folders, listed alongside the modding guide for each.

Stellaris/common/

Folder/File	Summary	Guides
agendas	Agendas are given to leader-candidates in Oligarchic government-forms	Agendas
ambient_objects	References used by code to spawn ambient objects	Models
anomalies	Events that occur for research ships	Anomalies
armies	Definitions for army types	Armies
army_attachments	Definitions for attachments that can be added to armies	Armies
attitudes	Definitions containing the restrictions for each attitude used by the AI	AI
buildable_pops	Definitions for buildable pops. i.e. Robots	Pops
buildings	Setup for buildings constructable on planets, and those given through events	Buildings
colors	Color definitions used for the country color selection	Countries
component_flags	List of flags used by the AI for selecting components	Ships
component_sets	List of the sets of components used by ships	Ships
component_tags	Used to group components together for common modifiers	Ships
component_templates	Attribute setup for each weapon and the templates used for ships	Ships
country_types	Rules for each country within the game.	Countries
defines	Basic game behaviors and settings	Defines
deposits	Setup for the deposits of resources found on planets	Planets
diplo_phrases	Setup for the logic behind the diplomatic phrases used between countries.	AI
diplomatic_actions	Setup for the rules for diplomatic actions.	Gameplay
edicts	Setup for the edicts used by planets and countries.	Edicts
ethics	Setup for ethics, controlling their modifiers and categories	Ethics
event_chains	Setup for the event chains used in the events folder	Event chains
fallen_empires	Sets up the countries and system initializer used for fallen empires	Systems
game_rules	Logic used for various game actions, i.e. can_enslave_pop. Logic here does not override hardcoded rules.	Gameplay
global_ship_designs	Designs used by the ship designer for each species	Ships
governments	Setup for the governments.	Governments
graphical_culture	Controls the lighting used for ships, which differs between graphical cultures.	Species
mandates	Controls the mandates used by factions	Mandates
name_lists	Sets up the names used for each species.	Species
observation_station_missions	Actions that can be done with observation stations depending on ethic choices.	Gameplay
on_actions	Events and actions that happens when you move, or do anything.	Events
opinion_modifiers	Opinion of Empires on other Empires depending on Political status and Ethics.	Opinion Modifiers
personalities	Shows the personalities of Empires AI traits and of Fallen Empires and enables editing them.	AI
planet_classes	The setup for all the planets and stars in the game.	Planets
planet_modifiers	Spawn chances planet modifiers (f.e. lush, hazardous weather, etc.).	Planets
policies	AI Policy grabbing (What order they take policies in)	Policies
pop_faction_types	Population faction types and personalities?	Pops
precursor_civilizations	Precursor civilization weightings	Planets
random_names	Lists of random names for Empires	Gameplay
scripted_effects	Events that give buffs or de-buffs (effects).	Gameplay
scripted_triggers	Scripted events and how they trigger.	Gameplay
section_templates	Different Ship AI and how it acts.	Ship
sector_types	Types of sectors and how they act.	Gameplay
ship_behaviours	Standard ship behaviours.	Ship
ship_sizes	Sizes of the Ships.	Ship
solar_system_initializers	Defines starting systems for players, AI, event systems, hostile systems, etc.	Systems
spaceport_modules		Planets
special_projects		Special Projects
species_classes		Species
star_classes	Types of solar systems (NOT individual stars themselves!)	Systems
start_screen_messages		Gameplay
static_modifiers		Gameplay
strategic_resources		Planet
subjects		Gameplay
technology		Technology
terraform		Planets
tile_blockers		Planets
traits		Traits
triggered_modifiers		Gameplay
war_demand_counters		Wars
war_demand_types		Wars
achievements.txt		None
alerts.txt		Gameplay
message_types.txt		Gameplay

Stellaris/events/

Folder/File	Summary	Guides
example_events.txt	Contains the event code for a set of events.	Events

Stellaris/flags/

Folder/File	Summary	Guides
*.dds	A flag image file.	Flags
colors.txt	Sets up the allowed colors for flags and the randomizable combos.	Flags

Stellaris/fonts/

File	Summary	Guides
fonts.asset	Sets up the fonts used by the game.	Fonts

Stellaris/gfx/

Folder/File	Summary	Guides
advisorwindow	Sets up the 3D view for the advisor	Graphics
arrows	Contains the images used by various arrows ingame.	Graphics
cursors	Contains the cursor files/images used ingame.	Graphics
event_pictures	Contains the pictures used in events.	Events
fonts	Contains the font files used ingame.	Fonts
FX	Contains the FX shaders used ingame.	Graphical Effect
interface/	Contains the images used for interfaces ingame.	Graphics
interface/anomaly	Contains the images used for the anomaly mechanic	Graphics
interface/buttons	Contains the images used for buttons	Graphics
interface/diplomacy	Contains the images used for the diplomacy interface.	Graphics
interface/elections	Contains the images used for the election interface.	Graphics
interface/event_window	Contains the images used for the event window.	Graphics
interface/flags	Contains the image masks used for flags.	Graphics
interface/fleet_view	Contains the images used for fleets.	Graphics
interface/frontend	Contains the images used for the frontend interface.	Graphics
interface/government_mod_window	Contains the images used for the government modification interface.	Graphics
interface/icons	Contains the icons used for everything in the game.	Graphics
interface/main	Contains the images used for generic actions.	Graphics
interface/old	Contains the images used from EU4	Graphics
interface/outliner	Contains the images used for the outliner interface.	Graphics
interface/planetview	Contains the images used for the planet view interface.	Graphics
interface/progressbars	Contains the images used for progress bars ingame.	Graphics
interface/ship_designer	Contains the images used for the ship designer interface.	Graphics
interface/situation_log	Contains the images used for the situation log interface.	Graphics
interface/sliders	Contains the images used for sliders ingame.	Graphics
interface/system	Contains the images used for the system view interface.	Graphics
interface/tech_view	Contains the images used for the technology view interface.	Graphics
interface/tiles	Contains the images used for the tile view interface.	Graphics
interface/topbar	Contains the images used for the topbar interface.	Graphics
interface/waroverview	Contains the images used for the war view interface.	Graphics
keyicons	Contains the images used for button presses ingame.	Graphics
lights	Contains the logic used for the light effects ingame.	Graphical Effect
loadingscreens	Contains the images used for loadscreens.	Graphics
models	Contains the model .mesh files and images.	Models
models/portraits	Contains the portrait .mesh files and images.	Portraits
particles	Contains the logic and images used for particles.	Graphics
pingmap	Contains the logic used for pings.	Graphics
portraits	Contains the logic used for portrait images.	Portraits
projectiles	Contains the logic used for projectiles.	Graphics
shipview	Contains the logic used for ship view.	Graphics
worldgfx	Contains the logic and images used for world graphic effects.	Graphics

Stellaris/interface/

Folder	Summary	Guides
*.gfx	Controls the assignment of image to interface variable.	Interfaces
*.gui	Controls the visual logic of an interface.	Interfaces

Stellaris/localisation/

File	Summary	Guides
*l_english.yml	Contains English localisation	Localisation
*l_french.yml	Contains French localisation	Localisation
*l_german.yml	Contains German localisation	Localisation
*l_polish.yml	Contains Polish localisation	Localisation
*l_russian.yml	Contains Russian localisation	Localisation
*l_spanish.yml	Contains Spanish localisation	Localisation
*l_braz_por.yml	Contains Brazilian/Portuguese localisation	Localisation

Stellaris/map/

Folder/File	Summary	Guides
galaxy	Contains the galaxy options. You cannot add new ones currently.	Galaxies
setup_scenarios	Controls the logic for different sizes of galaxies.	Galaxies

Stellaris/music/

Folder/File	Summary	Guides
*.ogg	A music file.	Music
songs.asset	Controls the assignment of music to a code name, and sets the volume of playback.	Music
songs.txt		Music

Stellaris/prescripted_countries/

Folder/File	Summary	Guides
*.txt	Contains a pre-scripted setup for a country. Listed on the side ingame.	Galaxies
setup_scenarios	Controls the logic for different sizes of galaxies.	Galaxies

Stellaris/sound/

Folder/File	Summary	Guides
*.asset	Sets up sounds.	Sound
*.wav	A sound file.	Sound

Overwriting Specific Elements

Occasionally, it is possible to overwrite a specific game element without needing to replace the entire vanilla file. In some cases adding a element with a similar identifier into another file will duplicate that element for the game. But in other cases, the version that comes first (First In, Only Served; FIOS)/last (Last In, Only Served; LIOS) will be used instead. . The order in which files are processed is based on ASCIIbetical order of the filenames. If the names are the same, they'll be processed based on the reverse-ASCIIbetical order of the mod display name, with vanilla always being first (if it's at the top of the mod list, it'll be loaded last). Note that if there are multiple mods with the same display name, only the one whose mod file comes first, will be used.

Note that this feature is not documented and thus might be subject to arbitrary changes between versions.

Common Folder

A-N (Agendas -
Notification Modifiers)

File Type	Overwrite Type	Error Log	Notes
Agendas	LIOS	Object key already exists
AI Budget
Ambient Objects
Anomalies	LIOS	Object key already exists
Armies	LIOS	Object key already exists
Ascension Perks	LIOS	Object key already exists
Asteroid Belts
Attitudes	LIOS	Object key already exists
Bombardment Stances	LIOS	Object key already exists
Buildings	LIOS	Object key already exists
Button Effects
Bypass	LIOS	Object key already exists
Casus Belli	LIOS	Object key already exists
Colony Types	LIOS	Object key already exists
Colors
Component Sets	FIOS	Object key already exists
Component Tags
Component Templates	FIOS	Object key already exists
Country Customization
Country Types	LIOS	Object key already exists
Decisions	LIOS	Object key already exists
Defines	LIOS	[none]	The block the define is in must be included as well. E.g: NGameplay = { POLICY_YEARS = 10 }
Deposit Categories
Deposits	LIOS	Object key already exists
Diplomatic Phrases
Diplomatic Economy	LIOS	Object key already exists
Diplomatic Actions	LIOS	Object key already exists
Districts	Dupl (Last)	Object key already exists	Breaks max districts modifier
Economic Categories
Edicts	LIOS	Object key already exists
Ethics	LIOS	[none]	Might break "selected ethic" graphic
Event Chains	FIOS	[none]
Fallen Empires
Game Rules	LIOS	[none]
Global Ship Designs
Governments	LIOS	Object key already exists
├───Authorities	LIOS	Object key already exists
└───Civics	LIOS	Object key already exists
Graphical Culture
Leader Classes	LIOS	Object key already exists
Mandates	LIOS	Object key already exists
Map Modes	LIOS	Object key already exists
Megastructures	LIOS	Object key already exists
Name Lists
Notification Modifiers

O-Z (Observation Station
Missions - War Goals)

File Type	Overwrite Type	Error Log	Notes
Observation Station Missions
On Actions	NO	[none]	Cannot modify existing entries
Opinion Modifiers	LIOS	[none]
Personalities	LIOS†	Object key already exists
Planet Classes	LIOS	[none]
Planet Modifiers	LIOS	Object key already exists
Policies	LIOS	Object key already exists
Pop Categories	LIOS	Object key already exists
Pop Faction Types	LIOS	Object key already exists
Pop Jobs	N/A	[none]	Neither entry used
Precursor Civilizations
Random Names
Scripted Effects	LIOS	Object key already exists
Scripted Localisation
Scripted Triggers	LIOS	Object key already exists
Scripted Variables	FIOS	Variable name taken
Section Templates	FIOS	Duplicate section template found
Sector Focuses	LIOS	Object key already exists
Sector Types
Ship Behaviors	FIOS	Behavior name already exists
Ship Sizes	LIOS	Object key already exists
Solar System Initializers		Initializer already exists
Special Projects	FIOS	Object key already exists
Species Archetypes	Dupl (Last)	Object key already exists	Breaks bonus trait points modifier
Species Classes	LIOS	Object key already exists
Species Names
Species Rights	LIOS	Object key already exists	Effect tooltips are independent of the effects
Star Classes	FIOS
Starbase Buildings	LIOS	Object key already exists
Starbase Levels	LIOS	Object key already exists
Starbase Modules	LIOS	Object key already exists
Starbase Types	LIOS	Object key already exists
Start Screen Messages
Static Modifiers	FIOS	[none]
Strategic Resources	FIOS	[none]
Subjects	LIOS	Object key already exists
System Types	LIOS	Object key already exists
Technology	LIOS	Duplicate technology
└───Tiers	LIOS
Terraform (Links)	Dupl	[none]
Trade Conversions	LIOS	Object key already exists	Trade Policy
Tradition Categories	LIOS	Object key already exists
Traditions	LIOS	Object key already exists	Effect tooltips are independent of the effects
Traits	Dupl	[none]
War Goals	LIOS	Object key already exists

FIOS - First in, only served

LIOS - Last in, only served

Dupl - Duplicates

Dupl (Last) - Technically duplicates, however only last is used (breaks autogenerated modifiers)

Dupl (First) - Technically duplicates, however only first is used (breaks autogenerated modifiers)

Please note that these have not been extensively tested; Entries listed as FIOS or LIOS might actually be Dupl, Dupl (First), or Dupl (Last)

Localisation Folder

Localisation folder is not consistent.

It's possible to overwrite by LIOS and FIOS.

A more sure-fire way to overwrite localization is to add a "replace" folder inside and add the parts your mod is trying to overwrite there.

Events Folder

Events are treated as FIOS

Tools & utilities

• Notepad++ - Powerful editor to change files.
• WinMerge - Contrasts the difference between two text files. Useful for updating mods.
• VS Code - Powerful, hackable, free open source editor from Microsoft.
• Maya exporter - Clausewitz Maya Exporter to create your own 3D models.
• Spaceship Generator - A Blender script to procedurally generate 3D spaceships
• Static Galaxy Generator - A static galaxy generator and editor for your mods. (How to use)
• Steam Workshop - The place for where you can share your creations with other players.
• Sublime Text - Powerful, moddable, hackable text editor. Install packages as your needs evolve.
• Stellaris Modding Subreddit
• The Stellaris Modding Den - the central modding discord for Stellaris.

External links

Stellaris Dev Diary #31 - Modding (Scripting Anomalies)
Stellaris Dev Diary #32 - Modding art

See also

• Mods

References

Modding