pmilleroly27: welp I goofed, I wasn't launching the proper .exe. My example is Divinity Original Sin Enhanced Edition. I tried Launching "Launch Divinity - Original Sin Enhanced Edition", which is a shortcut in the "Divinity - Original Sin Enhanced Edition" folder, but the real .exe is located in Divinity - Original Sin Enhanced Edition/Shipping/EoCapp.
Of course that did not work since the shortcut points to the original folder of the game which might be different than the one you used before.
pmilleroly27: Unfortunately I deleted my GOG folder so I can test if that works. In Steam I test Batman Arkham Origin. I only add library and ran the game. No verify stuff, just a first time start up then launched without an issue.
If you simply copy the library folder to the steam directory steam automatically does a verify (checking existing files) when you click - play game or install a game. Steam did NOT notice that you changed your OS but it noticed that the game was removed - therefore it reinstalls the game (by checking the files and downloading missing ones) and does a first lauch install. Like I said - with GOG Galaxy verify game files should do the same. But yes, if you simply remove the gamefiles without uninstalling them Galaxy will only tell you that the installation is corrupt and probably asks you to reinstall or do a verify.
