Download the latest release and follow the instructions in HOW TO INSTALL.txt
To install mods after installing, just place them in your Mods folder in Risk of Rain 2!
This is required to provide Reflection.Emit, as the .NET Standard shipped with the game does not support it. These are taken from Unity's Editor for 4.5. They can be found in net4.5 and must be put in the Managed folder if you build this yourself.
premake5 <compiler> (for example with Visual Studio 2017 premake5 vs2017)readyrelease.exe in the main folderrelease.zip for you to distribute.