Absolver - Boss re-matches are locked behind an online requirement. Boss loot too. As well as some techniques that can be used in offline play but can only be learned online. Absolver also installs the invasive EAC anti-cheat software even for single player and won’t start without it.
GOG has DRM, they call it Galaxy.
It’s not a DRM, it is just a launcher.
https://www.gog.com/forum/general/drm_on_gog_list_of_singleplayer_games_with_drm/page1
Games that are multiplayer will usually use drm, yea.
The thousands of other games do not.
The very first game on the list;
Ok
I don’t think it’s required for any titles.
Would still be nice if they’d allow you to run games without the launcher open (assuming you use it to install them) though.