jtnix: Just upgraded to a new PC and moved an SSD with my GOG Games install folder on it.
With the new Windows PC, I just installed GOG Galaxy then changed 'Game installation folder' to the folder on the SSD I moved over.
Next, I installed games from the Owned Games tab in Gog Galaxy. Games I had already downloaded on the moved SSD installed quickly since I had most of the data files already. There were pauses near the end of each install, I assume to set up registry and config entries I was missing.
After that I was able to run each game no problem - tested No Man's Sky, Disco Elysium, Pathfinder and older games like Tomb Raider and Thief ran fine without having download it all again.
Good to know. Thanks