Victoria 3 Mod Development

Guide for creating and modifying Victoria 3 mods using Paradox's scripting language.

Quick Start

Mod Structure

Every Victoria 3 mod requires:

• .mod descriptor file in Documents/Paradox Interactive/Victoria 3/mod/
• Mod folder with content in subdirectories:
  • common/ - Game logic (decisions, buildings, laws, technologies, etc.)
  • events/ - Event files
  • localization/ - Localization files (YAML format)
  • gfx/ - Graphics assets
  • gui/ - GUI modifications

Basic .mod File Format

version="1.0.0"
tags={
	"Gameplay"
}
name="My Mod"
supported_version="*"
path="mod/MyMod"
remote_file_id=""

Common Modding Tasks

Creating Decisions

Decisions go in common/decisions/. Format:

my_decision = {
	is_shown = {
		# Conditions for decision to appear
		is_ai = no
	}
	possible = {
		# Conditions for decision to be available
		bureaucracy > 100
	}
	when_taken = {
		# Effects when decision is taken
		add_modifier = {
			name = my_modifier
			days = 365
		}
	}
	ai_chance = {
		base = 0
	}
}

Creating Events

Events go in events/. Format:

namespace = mymod

mymod.1 = {
	type = country_event
	
	title = mymod.1.t
	desc = mymod.1.desc
	
	option = {
		name = mymod.1.a
		# Option effects
	}
}

Localization

Localization files go in localization/<language>/ as YAML:

l_english:
 mymod.1.t:0 "Event Title"
 mymod.1.desc:0 "Event description."
 mymod.1.a:0 "OK"

Common File Types

• Decisions: common/decisions/*.txt
• Events: events/*.txt
• Buildings: common/buildings/*.txt
• Laws: common/laws/*.txt - See Creating Laws for detailed guide
• Law Groups: common/law_groups/*.txt - Required for laws
• Technologies: common/technology/*.txt
• Cultures: common/cultures/*.txt
• Countries: common/country_definitions/*.txt
• Modifiers: common/static_modifiers/*.txt
• Scripted Effects: common/scripted_effects/*.txt
• Scripted Triggers: common/scripted_triggers/*.txt

Creating Laws

Quick example:

# 1. Create law group (common/law_groups/my_group.txt)
my_law_group = {
    law_group_category = economy
}

# 2. Create law (common/laws/my_law.txt)
my_custom_law = {
    group = my_law_group
    icon = "gfx/interface/icons/law_icons/my_law.dds"
    progressiveness = 50
    modifier = {
        country_construction_efficiency_add = 0.1
    }
}

# 3. Add localization (localization/english/my_law_l_english.yml)
# my_custom_law:0 "My Custom Law"

See Creating Laws for complete guide.

Syntax Guidelines

Scope Operators

• ROOT - Original scope
• THIS - Current scope
• FROM - Previous scope
• PREV - Previous scope in chain

Common Conditions

• is_ai = yes/no - Check if AI controlled
• has_modifier = <name> - Check for modifier
• has_technology_researched = <tech> - Check technology
• bureaucracy > <value> - Numeric comparisons
• owns_entire_state_region = <state> - State ownership

Common Effects

• add_modifier = { name = <name> days = <days> }
• set_variable = { name = <name> value = <value> }
• add_technology_researched = <tech>
• trigger_event = { id = <event_id> }

Reference Files

For detailed information on specific modding areas, see:

• File Structure - Complete directory structure
• Syntax Reference - Detailed syntax guide
• Common Patterns - Common modding patterns
• Examples - Real-world examples
• Glossary - Comprehensive terminology dictionary
• CWTools Guide - Using CWTools for validation and auto-completion
• Creating Laws - Complete guide for creating new laws

Debugging

Common issues:

1. Syntax errors: Check brackets, quotes, and indentation
2. Missing localization: Ensure all keys exist in localization files
3. Scope errors: Verify scope operators are correct
4. File paths: Ensure files are in correct directories

Use game's error log to identify issues. Check Documents/Paradox Interactive/Victoria 3/logs/ for error messages.