Modding

Version

Please help with verifying or updating older sections of this article. At least some were last verified for version 2.5.

This article is for the PC version of Stellaris only.

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 with 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

Empire

Empire • Ethics • Governments • Civics • Origins • Mandates • Agendas • Traditions • Ascension Perks • Edicts • Policies • Relics • Technologies • Custom Empires

Pops	Jobs • Factions

Leaders

Leaders • Leader Traits

Species

Species • Species Traits

Planets

Planets • Planetary Feature • Orbital Deposit • Buildings • Districts • Planetary Decisions

Systems

Systems • Starbases • Megastructures • Bypasses • Map

Fleets

Fleets • Ships • Components

Land Warfare

Armies • Bombardment Stance

Diplomacy

Diplomacy • Federations • Galactic Community • Opinion Modifiers • Casus Belli • War Goals

Events

Events • Anomalies • Special projects • Archaeological Sites

Gameplay

Gameplay • Defines • Resources • Economy

Dynamic modding

Dynamic modding • Effects • Conditions • Scopes • Modifiers • Variables • AI

Media/localisation

Maya exporter • Graphics • Portraits • Flags • Event pictures • Interface • Icons • Music • Localisation

Other

Console commands • Save-game editing • Steam Workshop

Guidelines[edit]

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, or the Visual Studio Code Extension L13 Diff ), 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 and .mod files.
Use UTF-8 with BOM for localization and name list 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[edit]

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[edit]

OS	Path
Linux	`~/.local/share/Paradox Interactive/Stellaris/mod`
Windows	`…\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[edit]

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. Ignored in the old launcher.
- image.ext – PNG and JPEG files are supported. With the new 2.4 launcher, must be a PNG named thumbnail.png

modname.mod and descriptor.mod both contain the mod information that the launcher uses when displaying the mod and uploading it.
The 2.4 launcher prefers descriptor.mod and will modify modname.mod to match the information in descriptor.mod, however if the file is not found, it'll use the information in modname.mod. The pre-2.4 launcher ignores it.
The path="XXX" is not needed in descriptor.mod.
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`	modname.mod: Yes descriptor.mod: No (Ignored)	Defines which folder is the mod's folder. It is relative to …\\Documents\\Paradox Interactive\\Stellaris folder. Note: Stellaris uses (Unix) slash `/` instead of (Microsoft) backslash `\` (or `\\`).	`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. With the new 2.4 launcher, this must be a PNG file named `thumbnail.png`.	`picture="thumbnail.png"`
`tags`	No	List of tags for Steam Workshop. Using tags besides the predefined ones may prevent uploading on Paradox Mods. 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"`

The data structure is similar to the proprietary Valve Data Format.^[1]

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[edit]

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.png.

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

You can always update the thumbnail at any time by updating the mod (unless you are only a co-author).

Creating a mod[edit]

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[edit]

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

Note that if you subscribe to an uploaded version of your mod while you still have the .mod file of your original mod in the mods folder, the uploaded mod will likely not work.

Game data[edit]

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[edit]

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

Stellaris/common/[edit]

Folder/File	Summary	Guides
agendas	Agendas are given to leader-candidates in Oligarchic government-forms	Agendas
ai_budget	Determine how AI should handle resources.	AI
ambient_objects	References used by code to spawn ambient objects	Models
archaeological_site_types	Definitions for Archaeological Sites to be discovered and delved by Science Ships.	Ancestral Relics
anomalies	Events that occur for research ships	Anomalies
armies	Definitions for army types	Armies
~~army_attachments~~ (Deprecated)
artifact_actions	Definitions for Artifact Actions.	Ancestral Relics
ascension_perks	Definitions for Ascension Perks.	Traditions
attitudes	Definitions containing the restrictions for each attitude used by the AI	AI
bombardment_stances	Definitions of bombardment stances.	Bombardment Stances
~~buildable_pops~~ (Deprecated)
buildings	Setup for buildings constructable on planets, and those given through events	Buildings
button_effects	Definitions for button effects.	Graphics
bypass	Definitions for bypasses (gateway, worm hole and l-gate)	Bypasses
casus_belli	Definitions for casus belli.	Wars
colony_automation	Definitions for colony autobuild types.	Colony Automations
colony_automation_exceptions	Definitions for colony autobuild types.	Colony Automations
colors	Color definitions used for the country color selection	Countries
~~component_flags~~ (Deprecated)
component_sets	List of the sets of components used by ships	Ships
component_slot_templates	Slot templates to be used with ship sections.	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
decisions	Definitions for planetary decisions.	Decisions
defines	Basic game behaviors and settings	Defines
deposit_categories	Deposit categories relevant to deposit generation.	Planet Generation
deposits	Setup for the deposits of resources found on planets as well as blockers spawned on habitable planets.	Planet Generation
diplo_phrases	Setup for the logic behind the diplomatic phrases used between countries.	AI
diplomacy_economy	Economy units based on diplomacy. Diplomatic upkeeps like influence upkeep of Federations are defined here.	Diplomacy
diplomatic_actions	Setup for the rules for diplomatic actions.	Diplomacy
districts	Definitions for districts.	Buildings
economic_categories	Definitions for economic categories.	Economy
economic_plans	Definitions for AI economy plans.	AI
edicts	Setup for the edicts used by 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
federation_law_categories	Definitions for federation law categories.	Diplomacy
federation_laws	Definitions for federation laws.	Diplomacy
federation_perks	Definitions for federation perks.	Diplomacy
federation_types	Definitions for federation types.	Diplomacy
galactic_focuses	Definitions for galactic focuses relevant to the Galactic Community.	Diplomacy
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
lawsuits	Unused.
leader_classes	Definitions for leader classes.	Leaders
mandates	Controls the mandates used by factions	Mandates
map_modes	Definitions for map modes to be used in the galaxy view.	Map Modes
megastructures	Definations for megastructures.	Megastructures
name_lists	Sets up the names used for each species.	Species
notification_modifiers	A variation of static modifiers. They have no modifiers and can only be added to empires.	Static Modifiers
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.).	Planet Generation
policies	AI Policy grabbing (What order they take policies in)	Policies
pop_categories	Definitions for pop categories (social strata).	Pop Jobs
pop_faction_types	Population faction types and personalities	Pop Factions
pop_jobs	Definitions for pop jobs.	Pop Jobs
precursor_civilizations	Precursor civilization weightings	Planets
random_names	Lists of random names for Empires	Gameplay
relics	Definitions for Relics.	Ancestral Relics
resolution_categories	Definitions for resolution categories relevant to the Galactic Community.	Diplomacy
resolutions	Definitions for resolutions relevant to the Galactic Community.	Diplomacy
scripted_effects	Pre-defined blocks of Effects to be called elsewhere.	Dynamic
scripted_loc	Pre-defined methods to provide text based on the scoped object's attributes.	Dynamic
scripted_triggers	Pre-defined blocks of Conditions to be called elsewhere.	Dynamic
scripted_variables	Pre-defined "@" variables to be called from other game files.	Dynamic
section_templates	Container of components that consist actual ships.	Ship
sector_focuses	Types of sectors and how they act.	Colony Automations
sector_types	Types of sectors and how they act.	Colony Automations
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~~ (Deprecated)
special_projects		Special Projects
species_archetypes	Definitions for species archetypes to give some shared attributes to species classes.	Species
species_classes	Definitions for species classes that are sets of species portraits.	Species
species_names	Definitions for species random names.	Species
species_rights	Definitions for species rights.	Species
star_classes	Types of solar systems (NOT individual stars themselves!)	Systems
starbase_buildings	Definitions for starbase buildings that each starbase can only have one of each of them.	Starbases
starbase_levels	Definitions for starbase levels.	Starbases
starbase_modules	Definitions for starbase modules.	Starbases
starbase_types	Definitions for starbase types. To players, no effects, flavor only. To the AI, a starbase auto-build guide.	Starbases
start_screen_messages	Messages that should be shown to the player at the start of the game.	Gameplay
static_modifiers	Blocks of Modifiers to be added to objects.	Static Modifiers
strategic_resources	Definitions for resources, not just strategic resources.	Economy
subjects	Definitions for subject types.	Diplomacy
system_types	Definitions for system types. No effects, flavor only.	Starbases
technology	Definitions for technologies.	Technology
terraform	Definitions for terraform methods.	Planets
trade_conversions	Definitions for trade value conversions.	Economy
~~tile_blockers~~ (Deprecated)
tradition_categories	Definitions for tradition groups.	Traditions
traditions	Definitions for traditions.	Traditions
traits	Definitions for species traits and leader traits.	Traits
~~triggered_modifiers~~ (Deprecated)
~~war_demand_counters~~ (Deprecated)
~~war_demand_types~~ (Deprecated)
war_goals	Definitions for war goals.	Wars
achievements.txt	Definitions for achievements. Modding this file doesn't make sense, since achievements are disabled for any "common" changing/expanding mods anyway.
alerts.txt		Messages
message_types.txt		Messages

Stellaris/events/[edit]

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

Stellaris/flags/[edit]

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/[edit]

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

Stellaris/gfx/[edit]

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/[edit]

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

Stellaris/localisation/[edit]

File	Summary	Guides
*l_simp_chinese.yml	Contains Chinese localisation	Localisation
*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/[edit]

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/[edit]

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/[edit]

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/[edit]

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

Overwriting Specific Elements[edit]

Occasionally, it is possible to overwrite a specific game element without needing to replace the entire vanilla file. In some cases adding an 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.^[2] 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[edit]

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
Artifact Actions	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	Breaks auto- generated modifiers
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	LIOS	Object key already exists	Breaks auto- generated modifiers
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	FIOS	A ship design already exists
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	DUPL/LIOS	[none]	`add_opinion_modifier` is LIOS
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	LIOS [?]	[none]	Breaks auto- generated modifiers
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	FIOS	Initializer already exists
Special Projects	FIOS	Object key already exists
Species Archetypes	LIOS	Object key already exists	Breaks auto- generated modifiers
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	FIOS	[none]	The first valid part for each location will be used and the rest discarded without issue.
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

NO – Cannot individually overwrite

Please note that not everything could be tested extensively.

Localisation folder[edit]

Localisation is likely LIOS

A guide for overwriting localisation can be found here.

Events folder[edit]

Events are treated as FIOS

Interface folder[edit]

Interface is likely LIOS

Tools & utilities[edit]

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.
Paradox Graphics – A Comprehensive Guide – In-depth documentation for preparing 3d models for Clausewitz engine games like Stellaris.

Advanced tips[edit]

For the bigger mods using a source control management tool (Git, …), it is handy to create a symbolic link between Stellaris mod folder and the working directory of the local repository, especially if the mod also has sub-mods. Note that you'll still need to copy the .mod file(s) manually, but they rarely change. Run the following command from the parent directory of main git folder, replacing:
- <mod_path_name> by the value of path attribute from .mod file
- <git_mod_folder> by the name of the sub-folder that contain mod data (folders common, decisions, events, etc…)

mklink /J "%USERPROFILE%\Documents\Paradox Interactive\Stellaris\mod\<mod_path_name>" ".\<git_mod_folder>"

Testing Mods[edit]

Certain, more obscure Console commands (that don't show up if you type 'help' in the console) are extremely useful in the process of testing a mod and more specific alterations.

observe – switches you to Observer Mode. You will no longer play as any specific character – this will allow the game to run for a long period of time, uninterrupted. It also makes every invisible trait and secret religion visible.
run <filename.txt> – runs script in a txt file located in the in the Documents install directory. It will be executed from the player's scope. Useful for testing tricky scripts – you can just have the script open in a different window, run it, tweak the script, save it, and run it again – it will be recompiled every time.
reloadevents – reloads and recompiles every single event (may take a while depending on your hardware). Useful if you want to tweak an entire event or chain of events without rebooting the game every time. not yet implemented
~~reloadloc~~reload text – reloads the entire localisation table. Useful if you spot a typo while testing your mod, or if you are trying to fit as much text in an event frame as possible.