Modding Tutorials/Writing custom code

In addition to creating data for the game to use, you can also write code. You could probably write in any .NET language, but I’ve only tested C#.

1. Create a new class library project in your IDE of choice;
2. In your project, add references to these DLLs:
   

   (RimWorldInstallFolder)/RimWorld_Data/Managed/Assembly-CSharp.dll
   (RimWorldInstallFolder)/RimWorld_Data/Managed/UnityEngine.dll

3. In your project properties, change the target framework to .NET 3.5;
4. Create a new class in a new code file;
5. You’ll want to add these namespace to each of your source files as necessary;
   

   using UnityEngine;  	//For all Unity functionality, rendering, resource management
   using AI;		//RimWorld AI
   using Sound;	        //RimWorld sound subsystem
   using UI;		//RimWorld GUI
   

6. Write your class;
   1. Decompile source code to take a look at the game's existing code;
   2. If you still get stuck on anything, any modding questions can be asked on the subforum,
7. Compile your class into a .dll;
   1. Make sure your project's output type is "class library";
   2. Note: by default, Visual Studio will compile all the references of the project as well, so you’ll get a copy of UnityEngine.dll and Assembly-CSharp.dll and some others. You don’t need these. Just take YourModName.dll,
8. Place the .dll in the YourModName/Assemblies folder of your mod;
9. Reference the classes in your .dll from the xml data in the YourModName/Defs folder;
   1. Example: Create a new ThingDef with a <thingClass> that points to a class in your .dll,
10. The game should load your class now;
11. Optional: Release your source code.
    1. Most mods include a YourModName/Source folder with the full C# project in it for other modders to check out;
    2. Some mods include a Dropbox download link to their source code in the mod's topic. This is also a possibility.
       
       

See also

• You can find a small tutorial project here: Modding Tutorials/Assembly Modding Example