RimWorld is one of the best games for learning game mod development.

Unlike many games, you do not need advanced programming knowledge before creating something useful. A simple RimWorld mod can consist entirely of human-readable XML files.

When you need more advanced behavior, you can move into C#.

When you need to alter existing game behavior without replacing entire systems, you can use Harmony.

This makes RimWorld an excellent modding environment for both beginners and experienced developers.

This guide targets RimWorld 1.6.

By the end of this guide, you will understand how to:

• create a RimWorld mod from scratch
• understand the mod folder structure
• create About.xml
• create new items with XML
• create crafting recipes
• use RimWorld Defs
• add textures
• modify vanilla content safely
• use PatchOperations
• set up a C# development environment
• compile a RimWorld DLL
• create a C# mod class
• understand Harmony patching
• debug XML and C# errors
• organize larger projects
• support RimWorld 1.6
• upload your mod to Steam Workshop
• update a published Workshop mod safely

1. How RimWorld Mods Work

A RimWorld mod is essentially a folder containing content that RimWorld loads in addition to the base game.

A simple mod may contain only XML:

MyMod/
│
├── About/
│   └── About.xml
│
├── Defs/
│   └── ThingDefs/
│       └── Items.xml
│
└── Textures/
    └── ExampleMod/
        └── MyItem.png

A more advanced mod can also contain:

Assemblies/
Languages/
Patches/
Sounds/
Source/
LoadFolders.xml

and other resources.

The important concept is:

XML
=
data and definitions

C#
=
custom behavior

Harmony
=
altering existing behavior

You can create a surprising amount of content without writing any C#.

2. What Can You Mod?

Content	XML Required	C# Required
New resource	Yes	No
New weapon	Yes	Usually no
New apparel	Yes	Usually no
New recipe	Yes	No
New plant	Yes	Usually no
New research project	Yes	No
New building	Yes	Sometimes
New animal	Yes	Sometimes
New faction	Yes	Sometimes
New trait	Yes	Sometimes
New hediff	Yes	Sometimes
New UI	Possibly	Usually yes
New AI behavior	Possibly	Usually yes
New game mechanic	Possibly	Usually yes
Modify existing methods	No	Harmony/C#

For your first mod, XML is the best place to start.

3. What We Will Build

Our tutorial project will be called:

Example Survival Equipment

The first item will be:

Field Survival Kit

The player will be able to craft it using basic resources.

Later in the guide, we will add a C# component to demonstrate how an XML mod can evolve into a coded mod.

For internal identifiers we will use:

YOURTAG_

For example:

YOURTAG_FieldSurvivalKit

Replace YOURTAG with your own short developer or mod prefix.

Examples:

JSM_FieldSurvivalKit
ACME_FieldSurvivalKit
MYMOD_FieldSurvivalKit

Do not use generic Def names such as:

SurvivalKit
NewGun
Metal
SuperArmor

Another mod may use the same name.

4. Software You Need

Recommended tools:

RimWorld

You need RimWorld installed.

This guide targets:

RimWorld 1.6

Visual Studio Code

Useful for:

XML
C#
JSON
Git
project-wide search

Download:

https://code.visualstudio.com/

Visual Studio Community

Recommended once you begin writing C#.

Download:

https://visualstudio.microsoft.com/

Install:

.NET desktop development

For RimWorld C# development, use:

.NET Framework 4.7.2

Git

Recommended for larger projects.

https://git-scm.com/

5. Find the RimWorld Installation Directory

A typical Steam installation is:

C:\Program Files (x86)\Steam\steamapps\common\RimWorld\

You can also use:

Steam
→ RimWorld
→ Properties
→ Installed Files
→ Browse

6. Vanilla Files Are Your Best Documentation

Look inside:

RimWorld\Data\

The Core data contains vanilla definitions for:

weapons
resources
buildings
animals
plants
recipes
research
apparel

One of the best habits in RimWorld modding is:

Do not guess how a Def works if RimWorld already contains a similar example.

Want to create a rifle?

Find a vanilla rifle.

Want to create food?

Find a vanilla food ThingDef.

Want to create a crafting recipe?

Find a similar vanilla RecipeDef.

7. Where Local Mods Are Stored

Inside the RimWorld directory:

Mods/

Create:

RimWorld/
└── Mods/
    └── ExampleSurvivalEquipment/

Our beginner structure will look like:

ExampleSurvivalEquipment/
│
├── About/
│   ├── About.xml
│   └── Preview.png
│
├── Defs/
│   ├── ThingDefs_Items/
│   │   └── Example_Items.xml
│   │
│   └── RecipeDefs/
│       └── Example_Recipes.xml
│
└── Textures/
    └── ExampleMod/
        └── FieldSurvivalKit.png

Later we can add:

Assemblies/
Patches/
Source/
Languages/

8. Create About.xml

Create:

About/About.xml

Add:

<?xml version="1.0" encoding="utf-8"?>

<ModMetaData>

    <name>Example Survival Equipment</name>

    <author>Your Name</author>

    <packageId>yourname.survivalequipment</packageId>

    <supportedVersions>
        <li>1.6</li>
    </supportedVersions>

    <description>
Adds survival equipment and serves as an example project for learning RimWorld modding.
    </description>

</ModMetaData>

9. Understanding packageId

This line is extremely important:

<packageId>yourname.survivalequipment</packageId>

Think of it as the permanent technical identity of your mod.

Use a format such as:

author.modname

Examples:

yourname.survivalequipment
john.medicalexpansion
acme.weaponpack

Do not casually change your package ID after publication.

Other mods may later depend on it.

10. supportedVersions

For RimWorld 1.6:

<supportedVersions>
    <li>1.6</li>
</supportedVersions>

Only list versions you actually support.

11. Add Preview.png

Create:

About/Preview.png

A useful preview size is:

640 × 360

or:

1280 × 720

Use:

• readable text
• clear artwork
• a simple title
• consistent branding

12. Enable Your Empty Mod

Launch RimWorld.

Open:

Mods

Look for:

Example Survival Equipment

Enable it.

If your empty mod appears correctly, your metadata structure is working.

Do not build dozens of files before verifying this step.

13. RimWorld Defs

A Def is essentially a data definition.

Examples:

ThingDef
RecipeDef
Research