I want to upgrade the SSD in my laptop as I need more room. I want to re-install BG3 afterwards. I found my saves so I can back those up, but I don't see a way to back up my install files so I can reinstall the game without downloading it again. I did the original install with the GOG Galaxy app, so I have no clue how to re-install BG3 without downloading it again. It took well over an hour to download last time, and I my internet isn't slow, something like 250mega bits per second.

I think you should try this procedure:

1. Close Galaxy;
2. Backup the game's files from the installation directory to a safe location;
3. Upgrade the SSD;
4. Start Galaxy;
5. Start downloading/installing the game;
6. Pause the downloading process at the beginning;
7. Close Galaxy;
8. Restore the game's files back into the installation directory;
9. Restore the saved game data;
10. Start Galaxy, which should automatically find the game's files, hence considering the game completely downloaded;
11. Validate the game's files;
12. Play the game.

you just copy the games files over after i.e, you Don't need to download shit [see images]

once you have your game files copied over you point Galaxy [1 or 2] to the location of your game... Galaxy will scan for the exe and assuming you don't have a pirate copy i.e, the exe is actually there you are fine

Windows users should then press the verity \ repair option... this will not download much because the game files are all there but it will add an icon to launch the game and more important will tell Windows that the software is actually installed

edit: added image to show where it lives in Galaxy 2 ...by request ;)

Thank you ussnorway. That worked beautifully. Now if we can get the forums mods to sticky this info for the next guy, or gal.