Harmony  

This mod contains the C# library Harmony for all RimWorld mods.

Harmony is a library that is used by many mods. In RimWorld 1.x or older the library was included inside C# mods and there was no need to load it as a separate mod. However, RimWorld versions after 1.x changed that and including it in every mod is no longer possible so it needs to be loaded before any other mod. Place this mod all the way on top of the mod list and before Core.

FAQ

Q: I get lines like "Fallback handler could not load library" in my log!
A: These are not errors and can simply be ignored. There is nothing wrong (any mod that uses code will trigger those bogus messages)

Q: Why do I need this mod?
A: You don't need it but one of your mods depends on it to work correctly.

Q: What does it do?
A: Nothing. To be exact: stuff that mod programmers want and need. It cannot cause any errors by itself.

Q: Should this really go above the Core?
A: Yes, it must be first in the list.

Q: Does this work with RimWorld 1.x
A: No, there is no need for a Harmony mod in that version.

Q: Where can I find the non-Steam version?
A: GitHub link