Tips & Tricks

1. DnSpy: View → Options → enable Show hidden compiler generated types and methods. This is useful for seeing details such as the ordinal assigned to a lambda.

Development Environment Setup

This document details how to set up a RimWorld Multiplayer development environment.

Note: This guide is written for Visual Studio Code in Windows. If you want to use another IDE or OS, YMMV.

To build ensure you have .NET 8 or higher installed.

(Optional) Duplicated game installations

If you wish to have the option to play a "pristine" copy of the game, it is best to have a separate copy for development.

Windows Instructions

1. Navigate to your steamapps\common directory.
   • If you haven't changed the default library location in Steam this will be:
     C:\Program Files (x86)\Steam\steamapps\common
2. Copy the existing installation directory from RimWorld to RimWorldDev

Mac Instructions

1. Navigate to your steamapps\common directory.
   • If you haven't changed the default library location in Steam this will be:
     /Users/[username]/Library/Application Support/Steam/steamapps/common/.
2. Copy the existing installation directory from RimWorld to RimWorldDev
3. If Rimworld is not launched through Steam, it cannot connect to the Steam API, and things like workshop mods are unavailable. To resolve this create a file steam_appid.txt with contents 294100 in the /steamapps/common/RimWorldDev directory, alongside RimWorldMac.app

Note: You can do this multiple times, for example if you wanted a v1.6 Rimworld and a v1.5 Rimworld to do development in both environments.

This way the Steam copy in RimWorld is still pristine and can be used for standard play. And you have another copy in RimWorldDev that you can develop in.

(Optional) Separate game settings

You may want different settings depending on whether you're playing with friends, or doing development. With friends you likely want high-res, full-screen. During development you might like the game to be in Window mode, as small as possible (1024x768), and with Development mode enabled!

These instructions allow you to maintain separate game environments between "pristine" and "dev"

1. The game ships with a README file (steamapps\common\RimWorld\Readme.txt)
2. This file details a command-line switch to specify to the game where to store save files and config.
   • Note: The file also details a -quicktest option to fast-load into a tiny map.

Windows instructions

• Create a shortcut to the executable (RimWorldWin64.exe), and edit the shortcut details.
• After the target add the following text: -savedatafolder=DevSaveData
  • The target should now look like:
    
    
  • This specifies to save the config and games in a directory named DevSaveData in the same folder as the executable, eg steamapps\common\RimWorldDev\DevSaveData

Mac instructions

You can run the file from the command line and specify switches with a command like:

open -na /Users/[username]/Library/Application\ Support/Steam/steamapps/common/RimWorldDev/RimWorldMac.app --args -savedatafolder=DevSaveData

And if you're comfortable with Mac/Linux, you can make a shell script out of this easily enough. However many people may want a "shortcut" icon.

• Launch Automator
• Choose the "Application" type
• Add the Action "Library" > "Utilities" > "Run Shell Script"
• Set the Shell to /bin/bash
• Enter the following as your script:
  ​​​​open -na /Users/[username]/Library/Application\ Support/Steam/steamapps/common/RimWorldDev/RimWorldMac.app --args -savedatafolder=DevSaveData
  

• Save this as an Application, eg "RimWorldDev"

You can now add the new "Application" to your dock or desktop.

Clone Multiplayer Mod

Note: It's recommended to fork the source code to your own account/repository first, and clone that.

1. Navigate to your local game mods directory (eg steamapps\common\RimWorldDev\Mods)
2. Clone your code repository here (eg RimWorldDev\Mods\Multiplayer)

   Note: The build steps assume this relative location and copy binaries accordingly. Otherwise paths will need to be updated and/or binaries moved after each build.
   Note: While the GitHub documentation still refers to development, make sure to base your branch off dev.

   • The language files are maintained in a separate repository, but are linked to this repo as a "git submodule".
   • If you are cloning the Multiplayer repository for the first time, add the --recursive switch to your clone command, eg:
     ​​​​​​​​git clone --recursive [e-mail]:rwmt/Multiplayer.git
     

   • If you have already cloned the Multiplayer repository, you can fetch the Language files using the following command:
     ​​​​​​​​git submodule update --init --recursive
     

   • Alternatively you can copy the language files manually. Copy the Languages folder from an original mod installation (eg steamapps\workshop\content\294100\2606448745\1.5\Languages) to your mod folder (steamapps\common\RimWorldDev\Mods\Multiplayer\Languages)
3. If you navigate to the Multiplayer\Source directory you should be able to build the solution now.

The Source\Client\Multiplayer.csproj specifies to copy the compiled files back to the Mod directories Assemblies and AssembliesCustom as a build action.

Technically you can edit the code to make changes, build and RimWorld will respect these changes. The next section will detail how to perform debugging.

Debugging

The below instructions only apply to Windows.

dnSpy

This will allow you to inspect and eventually debug vanilla RimWorld code.

1. Install dnSpyEx.

Doorstop

Rimworld Doorstop allows you to enable the RimWorld Unity debugger. Follow the instructions on their page. Below is a summary.

1. Download the latest UnityDoorstop Release (select the release for your platform, eg doorstop_win_release_4.4.0.zip)
   • Unzip and place the files doorstop_config.ini and winhttp.dll into the RimWorld root directory (not mod directory)
2. Download the latest Rimworld Doorstop Release (select the Doorstop.dll)
   • Place the Doorstop.dll file into the RimWorld root directory (not mod directory)
3. Modify the doorstop_config.ini as per the Rimworld Doorstop instructions
   • Ensure you update the following settings:
     ​​​​​​​​debug_enabled=true
     ​​​​​​​​debug_address=127.0.0.1:55555
     

   • The port you choose only affects the debugger you are using. Visual Studio will default to port 56000, dnSpy defaults to port 55555.

Start a debug session

1. Open dnSpy.
2. Select File > Open, and select \RimWorldWin64_Data\Managed\Assembly-CSharp.dll
3. Set a breakpoint
   • For example, Assembly-CSharp > RimWorld > ActiveDropPod > PodOpen
4. From here you have two ways to debug:
   1. Launch the game first and connect the debugger
      • Run the game (\RimWorldWin64.exe)
      • From dnSpy, select Debug > Start Debugging
        • Debug engine: Unity (Connect)
        • IP Address: 127.0.0.1
        • Port: <whichever port was selected in doorstop_config.ini above>

        Hint: if you are using dnSpy and have the port set to the default 55555, then you don't need to enter any values. Simply select "Unity (Connect)" and click OK/hit enter.

   2. Allow dnSpy to launch the game to connect the debugger
      • From dnSpy, select Debug > Start Debugging
      • Debug engine: Unity
      • Executable: \RimWorldWin64.exe
5. Load the Multiplayer DLL into dnSpy
   1. From dnSpy select Debug > Windows > Modules (this will only be present while connected)
      • This will list all .dll files used by RimWorld.exe.
   2. Look for Multiplayer.dll and open it, but note that it may not appear right away.
      • If you can't find Multiplayer.dll, enter "data-" into the search bar
      • Double-click any module with names like data-0000022CFEF538E0. It usually has a version "0.5"
      • Check the left-side Assembly Explorer to see if Multiplayer.dll appears there.
6. Play the game! You can run multiple instances of the same \RimWorldWin64.exe and connect over LAN.
   Ensure you trigger an appropriate event for the breakpoint set: