I can only assume but ive seen complete code changes when the devs give them access.. sort of like how NightDive does with the games they bring to the table..

and as others have said wrappers and dll injectors combined with emulators and whatnot... its the big difference between a gog release and a steam release... the ability to know when they say it works "it will" or they work very hard with you and your machine to get it working...

I've seen them incorporate fixes from members into new patches for games before.

I dont think gog can do anything in terms of some games, unless there was a fan made crack / patch, for example checkout the Atlantis game.

https://www.gog.com/forum/atlantis_series#1481478197


They are as broken as they were since launch

true, but what realistic alternative is there really?
finding, contacting and verifying the person who created the crack 10+ years later seems near impossible. It wasn't like nowadays where crackers have websites and demonstrate there stuff on youtube :p
And I think publishers wouldn't be very happy if GOG put up a "thank you"-note somewhere to give them credit:
"Thank you FairLight, DEViANCE, etc. We appreciate your work" :p

I guess there is also the possibility that the crack was applied by the publisher before sending the "drm-free" version to GOG.