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.
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