[Hikikomori]

Plenty of games still being modded, even multiplayer, have you looked? And is no problem even in multiplayer as long as server enforces which mods are enabled.

GTA 5 RP mod is big, Arma series are very bare bone games where modders created scenarios and game types. Both pubg and dayz comes from arma 2 mods.

Steam Workshop has made it easier than ever before, no need to run 3rd party launchers or visit a number of sketch websites to get your mods.