Description
This mod removes the Singleplayer button from the Main Menu via a mixin. It is mainly meant to be used in mutliplayer modpacks, or being added as a dependency to other mods if you want to force people to play on a server, or prevent them from joining Singleplayer for some reason. The main reason is for event modpacks for creators - this way, players won't be able to test or find features in Singleplayer.
Source code will not be posted, as otherwise it would be possible to make a copy of this mod and disable the mixin.
I couldn't find any other sort of mod that existed like this, despite looking online frequently, so with the help of the folks in the NeoForge discord (mainly @RaymondBlaze, massive thanks to him), I set this up (it is quick and dirty, but it works).