There is no issue with gaming on LibreELEC, it's a supported (within reasonable hardware limits) Kodi feature and quite popular; if a little complicated to setup until you understand the moving parts. LE is using libretro emulators and emphasis is on "retro" which typically means pre-internet gaming so there probably aren't many online multiplayer ROMs around and research for that is probably easier done in gaming oriented forums where users are more familiar with ROM/emultator capabilities.