Idea group modding

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This article is about modding by adding new idea groups. Idea groups are found in /Europa Universalis IV/common/ideas.

Idea group structure[edit]

All idea groups, basic or national, should include 7 ideas and a bonus for completing the idea group. Idea groups can have any name, but names must be unique.

Individual ideas[edit]

Ideas consist simply of a name and a modifier, like so:

royal_navy = {
        navy_tradition = 0.25
        heavy_ship_power = 0.10

Any valid modifier that scopes to a country can be used in an idea entry. The names of ideas must each be localised. See below for details.


A bonus is the reward for completing an idea group. They use modifiers like individual ideas, but do not need to be localised. An example of a bonus:

bonus = {
        free_leader_pool = 1


Both basic and national ideas can use triggers. Triggers for national ideas determine which nations are assigned a national idea group, while triggers for basic ideas determine which nations can pick that set of ideas. Any valid trigger that scopes to a country can be used as a trigger for an idea group. This is an example of a trigger:

trigger = {
        OR = {
                tag = ENG
                tag = GBR

Basic ideas[edit]

Basic idea groups are groups that are unlocked with ADM tech levels, and are bought with monarch points. Basic idea groups in the vanilla game include Diplomatic, Offensive, and Economic. All basic idea groups must be assigned a category of ADM, DIP, or MIL like so:

category = MIL

Vanilla basic idea groups are found in 00_basic_ideas.txt. New basic ideas can be added either to that file or to a new file in the ideas folder.

Numbers of basic idea groups can be created in excess of the vanilla game's numbers, though too many may require advanced interface modding to display properly.


Unlike with national ideas, conditions can be given that make the AI more or less likely to pick an idea group. In the following example, the idea group will not be chosen by the AI if they have already picked the Humanist idea group.

ai_will_do = {
        factor = 1
        modifier = {
                factor = 0
                has_idea_group = humanist_ideas

National ideas[edit]

National ideas are determined upon loading the game, and can be “refreshed” for a country using the “swap_free_idea_group” effect in events and decisions. Typically idea groups are only swapped upon using a tag-switching decision.

All national idea groups should contain the line “free = yes” somewhere in the entry. This marks them as national rather than basic idea groups.

Vanilla national idea groups are found in 00_country_ideas.txt, zz_group_ideas.txt, and zz_default_idea.txt. New national idea groups can be added to these files or to new files in the ideas folder. Bear in mind the order of idea group assignment however, detailed below.


Unlike basic idea groups, national idea groups have traditions. These are modifiers that are present regardless of the number of ideas in the group that have been unlocked. They are determined like so:

start = {
        naval_morale = 0.20
        embargo_efficiency = 0.33

Assignment of national ideas[edit]

If a country meets the requirements for multiple national idea groups, it receives the first group it is eligible for in order of its location in the folder. File names are searched first, alphabetically. As such, 00_country_ideas.txt is always searched before zzz_default_ideas. This prevents any country that could have unique or group ideas from receiving generic national ideas. When a country is eligible for two sets of national ideas in the same file, it receives the group which comes first chronologically in the file. If the same TAG appears for two sets of national ideas with the same name in different files it tries to cram all of the ideas into the interface, so don't do this.


Basic idea group icons are stored in /Europa Universalis IV/gfx/interface/ideas and use the filename format idea_$IDEA_GROUP_NAME$.dds. (Icons may either be .tga or .dds.) To display an icon ingame, an entry must be added to /Europa Universalis IV/interface/ideas.gfx. For example, if one is adding an idea group named bureaucratic_ideas:

spriteType = {
	name = "GFX_idea_bureaucratic_ideas"
	texturefile = "gfx//interface//ideas//idea_bureaucratic_ideas.tga"
	noOfFrames = 1

	effectFile = "gfx/FX/buttonstate_linear.lua"


Main article: Localisation

This is an example of the text that should be localised:

KHM_ideas: "Khmer Ideas"
KHM_ideas_start: "Khmer Tradition"
KHM_ideas_bonus: "Khmer Ambitions"
staunch_theravada_buddhists_desc: "The Khmer people have fully embraced Theravada Buddhism as a reaction to the decadence of the past"
staunch_theravada_buddhists: "Staunch Theravada Buddhists"

Firstly, the name of the idea group itself is localised. "[group name]_start" localises tradition text. "[group name]_bonus" localises bonus text. Individual ideas are localised simply by using their names. Idea descriptions have the format of "[idea name]_desc".

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