Modifying Existing Content (General)

Overview

This guide provides strategies and techniques for modifying existing content in Civilization VII. Instead of creating new elements from scratch, we’ll focus on how to adjust, rebalance, and extend the game’s existing civilizations, leaders, units, buildings, and gameplay systems.

Prerequisites

Before modifying existing content, ensure you have:

A basic understanding of the Civilization VII modding architecture (see Modding Architecture)
Familiarity with the relevant database schemas (see Database Schemas)
Knowledge of the Age system (see Age Modules)
The game’s base files for reference
A working knowledge of creating content (see General: Creating Civilizations and General: Creating Leaders)

Planning Your Modifications

Modification Approaches

There are several approaches to modifying existing content:

Override Approach: Completely replace existing definitions
Addition Approach: Add new attributes or abilities to existing elements
Adjustment Approach: Alter specific values or parameters
Removal Approach: Disable or remove existing features
Hybrid Approach: Combine multiple approaches for comprehensive modifications

Design Principles for Modifications

When modifying existing content, consider these key principles:

Compatibility: Ensure modifications work with the base game and other mods
Balance: Make changes that improve gameplay without creating overpowered elements
Purpose: Have a clear goal for each modification
Theme Consistency: Maintain the thematic integrity of the original elements
Age Appropriateness: Respect the Age system when modifying content

Folder Structure Setup

Organize your modification mod with a clear folder structure:

<GAME_DATA>/Mods/your-mod-name/
├── civilization_overrides/   # Modifications to existing civilizations
├── leader_overrides/         # Modifications to existing leaders
├── unit_overrides/           # Modifications to existing units
├── building_overrides/       # Modifications to existing buildings
├── gameplay_overrides/       # Modifications to gameplay systems
├── text_overrides/           # Modified localization
└── your-mod-name.modinfo     # Mod metadata file

Implementation Process

1. Creating the Modinfo File

The .modinfo file defines your mod’s metadata and structure. Here’s a real example from Sukritact’s Inca Rework mod:

<?xml version="1.0" encoding="utf-8"?>
<Mod id="sukritacts_inca_rework" version="1" xmlns="ModInfo">
  <Properties>
    <n>Sukritact's Inca Rework</n>
    <Description>Reworks the Inca Civilization</Description>
    <Authors>Sukritact</Authors>
    <Package>Mod</Package>
  </Properties>
  <Dependencies>
    <Mod id="base-standard" title="LOC_MODULE_BASE_STANDARD_NAME"/>
  </Dependencies>
  <References>
    <Mod id="sukritacts_assorted_adjustments" title="Sukritact's Assorted Adjustments"/>
  </References>
  <ActionCriteria>
    <Criteria id="exploration-age-current">
      <AgeInUse>AGE_EXPLORATION</AgeInUse>
    </Criteria>
    <Criteria id="exploration-age-persist" any="true">
      <AgeInUse>AGE_EXPLORATION</AgeInUse>
      <AgeInUse>AGE_MODERN</AgeInUse>
    </Criteria>
    <Criteria id="always">
      <AlwaysMet></AlwaysMet>
    </Criteria>
  </ActionCriteria>
  <ActionGroups>
    <ActionGroup id="game-suk-inca-rework-always" scope="shell" criteria="always">
      <Properties>
        <LoadOrder>20</LoadOrder>
      </Properties>
      <Actions>
        <UpdateText>
          <Item>text/Suk_Inca_Rework_Text.sql</Item>
        </UpdateText>
      </Actions>
    </ActionGroup>
    <ActionGroup id="game-suk-inca-rework-EXPPLUS" scope="game" criteria="exploration-age-persist">
      <Properties>
        <LoadOrder>20</LoadOrder>
      </Properties>
      <Actions>
        <UpdateText>
          <Item>text/Suk_Inca_Rework_Text.sql</Item>
        </UpdateText>
        <UpdateDatabase>
          <Item>data/Suk_Inca_Rework_Traditions.sql</Item>
          <Item>data/Suk_Inca_Rework_Constructibles.sql</Item>
        </UpdateDatabase>
      </Actions>
    </ActionGroup>
    <ActionGroup id="game-suk-inca-rework-EXP" scope="game" criteria="exploration-age-current">
      <Properties>
        <LoadOrder>20</LoadOrder>
      </Properties>
      <Actions>
        <UpdateDatabase>
          <Item>data/Suk_Inca_Rework_Civics.sql</Item>
        </UpdateDatabase>
      </Actions>
    </ActionGroup>
  </ActionGroups>
</Mod>

Note how this mod uses the ActionCriteria to ensure certain modifications only apply during specific Ages, implementing Age-aware changes to the Inca civilization.

2. Modifying Civilizations

To modify an existing civilization, you can use either SQL or XML approaches. Many community modders prefer SQL for its efficiency. Here’s how Sukritact’s Inca Rework mod modifies the Terrace Farm improvement:

-- Remove restrictive terrain requirement
UPDATE Constructibles
SET AdjacentTerrain = NULL
WHERE ConstructibleType = 'IMPROVEMENT_TERRACE_FARM';

-- Rebalance yields
UPDATE Constructible_YieldChanges
SET YieldChange = 3
WHERE ConstructibleType = 'IMPROVEMENT_TERRACE_FARM' AND YieldType = 'YIELD_FOOD';

-- Delete existing modifier and create a new one
DELETE FROM ConstructibleModifiers WHERE ModifierId = 'MOD_SUK_TERRACE_FARM_FOOD';
DELETE FROM Types WHERE Type = 'MOD_SUK_TERRACE_FARM_FOOD_TYPE';
DELETE FROM Modifiers WHERE ModifierId = 'MOD_SUK_TERRACE_FARM_FOOD';

-- Add new modifier with different requirements
INSERT INTO ConstructibleModifiers
  (ConstructibleType, ModifierId)
VALUES
  ('IMPROVEMENT_TERRACE_FARM', 'MOD_SUK_INCA_REWORK_TERRACE_FARM_FOOD');

-- Define remaining modifier components...

This approach uses SQL UPDATE, DELETE, and INSERT statements to modify existing game elements, replace their functionality, and rebalance their effects.

3. Modifying Leaders

To modify an existing leader, create a file like leader_overrides/trajan_modifications.xml:

<?xml version="1.0" encoding="utf-8"?>
<Database>
  {/*Modify Leader Trait*/}
  <Traits>
    <Update>
      <Where TraitType="TRAIT_LEADER_TRAJAN_ABILITY"/>
      <Set Description="LOC_TRAIT_LEADER_TRAJAN_ABILITY_MODIFIED_DESCRIPTION"/>
    </Update>
  </Traits>
  
  {/*Add New Trait to Existing Leader*/}
  <LeaderTraits>
    <Row LeaderType="LEADER_TRAJAN" TraitType="TRAIT_LEADER_ADDITIONAL_ABILITY"/>
  </LeaderTraits>
  
  {/*Modify Leader Agenda*/}
  <Agendas>
    <Update>
      <Where AgendaType="AGENDA_TRAJAN"/>
      <Set Description="LOC_AGENDA_TRAJAN_MODIFIED_DESCRIPTION"/>
    </Update>
  </Agendas>
  
  {/*Modify Leader Categories*/}
  <LeaderCategories>
    <Delete>
      <Where LeaderType="LEADER_TRAJAN" CategoryType="LEADER_CATEGORY_MILITARY"/>
    </Delete>
    <Row LeaderType="LEADER_TRAJAN" CategoryType="LEADER_CATEGORY_EXPANSION"/>
  </LeaderCategories>
</Database>

4. Modifying Units

Here’s a real example from the Han Chukonu Rebalance mod showing how to modify an existing unit’s stats and functionality:

-- Update unit properties
UPDATE Units
SET Tier="2", Maintenance="1" 
WHERE UnitType="UNIT_NU";
  
UPDATE Units
SET Tier="3", Maintenance="2" 
WHERE UnitType="UNIT_NU_2";

-- Update combat stats
UPDATE Unit_Stats
SET Combat = "15", RangedCombat="20", Bombard="15" 
WHERE UnitType="UNIT_NU";
  
UPDATE Unit_Stats
SET Combat = "20", RangedCombat="25", Bombard="20" 
WHERE UnitType="UNIT_NU_2";
  
-- Update production costs
UPDATE Unit_Costs
SET Cost="45" 
WHERE UnitType="UNIT_NU";

-- Change unit replacement relationship
UPDATE UnitReplaces
SET ReplacesUnitType = "UNIT_ARCHER" 
WHERE CivUniqueUnitType="UNIT_NU";

-- Remove the second unit tier's replacement relationship
DELETE FROM UnitReplaces 
WHERE CivUniqueUnitType = "UNIT_NU_2";

-- Change tech tree unlocks
UPDATE ProgressionTreeNodeUnlocks
SET ProgressionTreeNodeType="NODE_TECH_AQ_BRONZE_WORKING" 
WHERE TargetType="UNIT_NU";

The mod also adds an entirely new bonus modifier for the unit:

-- Add new Iron resource bonus for the Chu Ko Nu
INSERT INTO Types ([Type], Kind) VALUES
  ("MOD_IRON_CHU_KO_NU_COMBAT_STRENGTH_TYPE", "KIND_EFFECT");

INSERT INTO GameModifiers (ModifierId) VALUES
  ("MOD_IRON_CHU_KO_NU_COMBAT_STRENGTH");

INSERT INTO DynamicModifiers (ModifierType, CollectionType, EffectType) VALUES
  ("MOD_IRON_CHU_KO_NU_COMBAT_STRENGTH_TYPE", "COLLECTION_ALL_UNITS", "EFFECT_UNIT_ADJUST_COMBAT_STRENGTH_PER_RESOURCE");
  
-- Set up requirements so it only applies to this unit type
INSERT INTO RequirementSets (RequirementSetId, RequirementSetType) VALUES
  ("MOD_IRON_CHU_KO_NU_COMBAT_STRENGTH_REQUIREMENTS", "REQUIREMENTSET_TEST_ALL");
  
INSERT INTO Requirements (RequirementId, RequirementType) VALUES
  ("MOD_IRON_CHU_KO_NU_COMBAT_STRENGTH_REQUIREMENTS_1", "REQUIREMENT_UNIT_TAG_MATCHES");
  
INSERT INTO RequirementArguments (RequirementId, Name, [Value]) VALUES
  ("MOD_IRON_CHU_KO_NU_COMBAT_STRENGTH_REQUIREMENTS_1", "Tag", "UNIT_CLASS_NU");

This mod demonstrates the “Hybrid Approach” - adjusting numerical values while also removing some functionality and adding new capabilities.

5. Modifying Buildings and Infrastructure

To modify existing buildings, create a file like building_overrides/building_modifications.xml:

<?xml version="1.0" encoding="utf-8"?>
<Database>
  {/*Modify Building Yields*/}
  <Building_YieldChanges>
    <Update>
      <Where BuildingType="BUILDING_GRANARY" YieldType="YIELD_FOOD"/>
      <Set YieldChange="3"/>
    </Update>
    <Row BuildingType="BUILDING_GRANARY" YieldType="YIELD_PRODUCTION" YieldChange="1"/>
  </Building_YieldChanges>
  
  {/*Modify Building Costs*/}
  <Building_Costs>
    <Update>
      <Where BuildingType="BUILDING_GRANARY" YieldType="YIELD_PRODUCTION"/>
      <Set Cost="60"/>
    </Update>
  </Building_Costs>
  
  {/*Modify Building Properties*/}
  <Buildings>
    <Update>
      <Where BuildingType="BUILDING_GRANARY"/>
      <Set Description="LOC_BUILDING_GRANARY_MODIFIED_DESCRIPTION"/>
    </Update>
  </Buildings>
</Database>

6. Modifying Gameplay Systems

To modify core gameplay systems, create a file like gameplay_overrides/gameplay_modifications.xml:

<?xml version="1.0" encoding="utf-8"?>
<Database>
  {/*Modify Research Costs*/}
  <TechnologyCosts>
    <Update>
      <Where TechnologyType="TECH_MINING"/>
      <Set Cost="70"/>
    </Update>
  </TechnologyCosts>
  
  {/*Modify Civic Costs*/}
  <CivicCosts>
    <Update>
      <Where CivicType="CIVIC_EARLY_EMPIRE"/>
      <Set Cost="65"/>
    </Update>
  </CivicCosts>
  
  {/*Modify Global Parameters*/}
  <GlobalParameters>
    <Update>
      <Where Name="COMBAT_EXPERIENCE_PER_KILL"/>
      <Set Value="6"/>
    </Update>
    <Update>
      <Where Name="CITY_GROWTH_RATE"/>
      <Set Value="1.5"/>
    </Update>
  </GlobalParameters>
</Database>

7. Modifying Text and Localization

Create localization files in text_overrides/modified_text.xml:

<?xml version="1.0" encoding="utf-8"?>
<GameData>
  <LocalizedText>
    {/*Modified Trait Description*/}
    <Row Tag="LOC_TRAIT_CIVILIZATION_ROME_ABILITY_MODIFIED_DESCRIPTION" Language="en_US">
      <Text>Modified description of Rome's civilization ability.</Text>
    </Row>
    
    {/*Modified Leader Ability*/}
    <Row Tag="LOC_TRAIT_LEADER_TRAJAN_ABILITY_MODIFIED_DESCRIPTION" Language="en_US">
      <Text>Modified description of Trajan's leader ability.</Text>
    </Row>
    
    {/*Modified Agenda*/}
    <Row Tag="LOC_AGENDA_TRAJAN_MODIFIED_DESCRIPTION" Language="en_US">
      <Text>Modified description of Trajan's agenda.</Text>
    </Row>
    
    {/*Modified Building Description*/}
    <Row Tag="LOC_BUILDING_GRANARY_MODIFIED_DESCRIPTION" Language="en_US">
      <Text>Modified description of the Granary building.</Text>
    </Row>
  </LocalizedText>
</GameData>

Age-Aware Modifications

Civilization VII’s Age system requires special consideration when modifying content. Sukritact’s mods demonstrate best practices:

<ActionCriteria>
  <Criteria id="exploration-age-current">
    <AgeInUse>AGE_EXPLORATION</AgeInUse>
  </Criteria>
  <Criteria id="exploration-age-persist" any="true">
    <AgeInUse>AGE_EXPLORATION</AgeInUse>
    <AgeInUse>AGE_MODERN</AgeInUse>
  </Criteria>
</ActionCriteria>

Then in ActionGroups:

<ActionGroup id="game-suk-inca-rework-EXP" scope="game" criteria="exploration-age-current">
  <Actions>
    <UpdateDatabase>
      <Item>data/Suk_Inca_Rework_Civics.sql</Item>
    </UpdateDatabase>
  </Actions>
</ActionGroup>

This ensures that modifications only apply during appropriate Ages. For example, civic tree changes only apply in the Exploration Age, while some improvements persist into the Modern Age.

SQL vs. XML Approach

While our guide has focused on both approaches, many successful community mods use SQL statements for modifications. Advantages include:

Concise Syntax: SQL modifications are often more compact than XML equivalents
Direct Database Manipulation: SQL directly modifies the game’s internal database
Combined Operations: Can perform updates, deletions, and insertions in a single file
Familiar to Database Users: Those with SQL experience find this approach intuitive

To use the SQL approach:

Create .sql files in your mod’s data directory
Reference them in your .modinfo file with <UpdateDatabase> actions
Use standard SQL commands: UPDATE, DELETE, INSERT, etc.
Organize files by category (traditions, units, constructibles, etc.)

Real-World Examples

Sukritact’s Inca Rework

This community mod reworks the Exploration Age Inca civilization:

Key Files

<GAME_DATA>/Mods/sukritacts_inca_rework/
├── data/
│   ├── Suk_Inca_Rework_Constructibles.sql  # Modifies Terrace Farm and Machu Pikchu
│   ├── Suk_Inca_Rework_Traditions.sql      # Reworks Inca traditions
│   └── Suk_Inca_Rework_Civics.sql          # Adjusts civic tree progression
├── text/
│   └── Suk_Inca_Rework_Text.sql            # Updates localization text
└── Sukritact's Inca Rework.modinfo         # Mod metadata with Age-aware criteria

Implementation Highlights

Removes restrictive terrain requirements from the Terrace Farm improvement
Rebalances yields to compensate for increased placement flexibility
Changes Machu Pikchu wonder to require adjacent Urban District instead of biome restriction
Implements Age-specific ActionGroups to ensure changes apply in appropriate game phases

Han Chukonu Rebalance

This focused mod rebalances the Han civilization’s unique unit:

Key Files

<GAME_DATA>/Mods/civmods-han_chukonu_rebalance-38120/
├── data/
│   └── BaseGame_Antiquity.sql  # Unit stat modifications and new Iron bonus
├── text/
│   └── (Localization text files)
└── han_chukonu_rebalance.modinfo

Implementation Highlights

Adjusts the Chukonu (Nu) unit’s combat stats, maintenance, and production costs
Changes its tech tree progression path
Adds a new bonus that gives +1 Combat Strength per Iron resource
Alters the unit replacement relationship with standard units

Testing Your Modifications

Install the Mod:
- Place your mod folder in the Civilization VII mods directory (<GAME_DATA>/Mods/)
- Enable the mod in the game’s mod menu
Initial Testing:
- Start a new game with the civilizations/leaders you’ve modified
- Verify that your changes appear correctly
- Test that modified abilities function as intended
- Check for any unintended side effects
Compatibility Testing:
- Test your mod alone with the base game
- Test your mod with official DLC content
- If possible, test with popular community mods
Performance Testing:
- Ensure your modifications don’t introduce performance issues
- Particularly important for mods that make systemic changes
Troubleshooting Common Issues:
- Changes not appearing: Check XML syntax and file references
- Game crashes: Look for conflicts with base game definitions
- Balance issues: Iteratively adjust values based on testing

Best Practices for Modifying Content

Document Your Changes: Keep detailed notes of what you’ve modified and why.
Use Clear Commenting: Include comments in your XML files explaining your changes.
Version Control: Use version numbers in your mod files to track iterations.
Incremental Changes: Test small changes before making large overhauls.
Respect Original Design: Try to understand why the original design choices were made before changing them.
Maintain Theming: Ensure your changes fit the historical and thematic context of the elements you’re modifying.
Gather Feedback: Share your mod with the community to get testing feedback.

Conclusion

Modifying existing content in Civilization VII provides an opportunity to refine the game to your preferences, rebalance elements you find too weak or too strong, and create a more personalized gaming experience. By carefully planning your modifications and following good modding practices, you can create high-quality mods that enhance the game while maintaining compatibility with other content. For additional guidance, refer to:

Documentation Index

​Overview

​Prerequisites

​Planning Your Modifications

​Modification Approaches

​Design Principles for Modifications

​Folder Structure Setup

​Implementation Process

​1. Creating the Modinfo File

​2. Modifying Civilizations

​3. Modifying Leaders

​4. Modifying Units

​5. Modifying Buildings and Infrastructure

​6. Modifying Gameplay Systems

​7. Modifying Text and Localization

​Age-Aware Modifications

​SQL vs. XML Approach

​Real-World Examples

​Sukritact’s Inca Rework

​Key Files

​Implementation Highlights

​Han Chukonu Rebalance

​Key Files

​Implementation Highlights

​Testing Your Modifications

​Best Practices for Modifying Content

​Conclusion

Overview

Prerequisites

Planning Your Modifications

Modification Approaches

Design Principles for Modifications

Folder Structure Setup

Implementation Process

1. Creating the Modinfo File

2. Modifying Civilizations

3. Modifying Leaders

4. Modifying Units

5. Modifying Buildings and Infrastructure

6. Modifying Gameplay Systems

7. Modifying Text and Localization

Age-Aware Modifications

SQL vs. XML Approach

Real-World Examples

Sukritact’s Inca Rework

Key Files

Implementation Highlights

Han Chukonu Rebalance

Key Files

Implementation Highlights

Testing Your Modifications

Best Practices for Modifying Content

Conclusion