Check out the original, if you haven't already. You can join the Discord server here.
GUN GODZ+ is a mod that aims to expand the game with various QOL changes and extra options. There are planned features like a modding API and online multiplayer, similar to NTT.
This project is still in a very early state, therefore you should avoid forking it for now unless it is for PRs adding to the project. I am currently still in the process of adding the basegame content while refining the internal systems.