The End is Nigh Official Discord Server
This is the best place to go for help with making mods. There are a few channels dedicated to it and plenty of people willing to help out.

TEIN Workshop Uploader
Use this to upload your mods to Steam Workshop. This uploader is adapted from the Quadrilateral Cowboy Workshop Uploader.

TEIN Mod Pack
These resources are pretty raw and mostly meant to help the community build better modding tools. See below for community-made unofficial tools.

This is the format that text-based data files in TEIN use. I've open sourced the code for it. Should be useful for anyone trying to make tools.


The End Is Nigh Modder's Manual
A community made guide to modding The End Is Nigh. A little bit out of date, but still a great resource for getting started. Rehosted here since the original's hosting expired.

Community Level Editor
This editor is way better than the official one provided in the mod pack. Just use this instead.

Newgrounds Audio Portal
The End Is Nigh uses rock/metal remixes of classical music for it's background music. It's cool that most mods have tried to keep consistent with this by searching up metal remixes of classical music on youtube, however while the compositions for these songs are in the public domain, people's individual recordings are still covered by copyright. Luckily, almost all of the music on the Newgrounds Audio Portal is covered by a CC-Noncommercial license, making it possibly the best resource out there to find music for your mods that won't get you in trouble.

Resource Unpacker Unpacks the .gpak resource files that come with The End Is Nigh.

(If any of these unofficial resource links stop working, please tweet at me with the updated links)

You can use any of the files provided to create non-commercial mods for The End Is Nigh.
You cannot use them for commercial projects, or non-commercial projects unrelated to The End Is Nigh.
Any mods you create with these resources must require people to own a copy of The End Is Nigh to play.
You cannot redistribute the exe or any non-modified game assets with your mods.