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Development Guide

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Will Corby edited this page May 5, 2025 · 4 revisions

Warning

Mod development needs a powerful PC!
Unexpected errors and issues may occur when editing networking code.
Running multiple instances of the game can be very taxing on your computer.
We're not responsible if you push your PC too hard.

Prerequisites

  • Visual Studio 2022.
  • Epic or Steam version of Outer Wilds.
  • Keyboard with numpad for in-game debug actions.

We recommend using the Outer Wilds Mod Manager, but you can use OWML on its own if you want.

Cloning and configuration

  • Clone QSB's source code.
  • Copy the file DevEnv.template.targets and rename it to DevEnv.targets.
  • In DevEnv.targets, edit the entry for <OwmlDir> to point to your installation of OWML. This should be the folder named OWML. If using the manager, you can find this directory by :
    • Legacy Manager : Press the "Mods Directory" button and go up a folder.
    • New Manager : Press the "..." button at the top, and select "Show OWML Folder".
  • QSB.sln should now be ready to open. This solution needs to be opened with Visual Studio 2022 or higher!

Multiple instances on Steam

If using the Steam version of Outer Wilds, you will need to create a file to allow you to run multiple instances of the game.

  • Navigate to your game install folder. You can find this by right-clicking on the game in Steam, and going Manage > Browse local files.
  • Create a file named steam_appid.txt.
  • In this file, write 753640 and save. This file will override some Steam DRM features and allow the game to be ran multiple times at once.
  • Either turn on "Force Exe" in the mod manager, or run OuterWilds.exe directly.

Important

Make sure "Debug Mode" is off in the mod manager, or else the game will sometimes run without mods. This is a weird OWML bug, I have no idea why it happens.

Building

Simply build the solution normally. (Build > Build Solution or CTRL-SHIFT-B)

The files will automatically be copied over to your OWML installation and be ready to play - no DLL copying needed.

For documentation reasons, here is the build flow :

  • MirrorWeaver is built.
  • EpicOnlineTransport is built.
  • EpicRerouter is built.
  • QSB is built.
  • Any .exe.config files are removed from the build.
  • QSB.dll is processed ("weaved") by MirrorWeaver. This injects all the boilerplate code that Mirror needs to function.
  • If needed/possible, any .dll or .exe files are copied to the Unity project.

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