BepInEx Installation Guide
WARNING
BepInEx is deprecated! only use this guide if you for some reason need a mod that requires it. Chances are, you don't, and none of your mods are going to work. Use MelonLoader instead!
1. Download BepInEx
To get legacy mods up and running, you need BepInEx. Downloads are on the BepInEx GitHub Releases. Pick the BepInEx_win_x64 version.
Unzip the file, then drag its contents over to your Gorilla Tag Directory.
Finishing up
You've successfully modded your game!
Go install some legacy mods, or something.