Typically, as I did when I played on steam, you open the launcher then hit "options" and you get a whole list of options to improve the quality and whatnot.

But, with the GOG version, that installer only has two buttons, "Install" and "Tech Support" with "Options" grayed out. When I hit "Install", the game tells me "Fallout New Vegas does not appear to be installed/ Try exploring your DVD-ROM drive and selecting setup.exe".

Such a file does not exist and it is installed, as I'm playing the game as long as I run it through the application and not the launcher. So how can I change the graphics settings if the launcher won't let me?

The only thing my "bethesda softworks" registry has in it is one called "default". No child folders. I'm fairly sure I have a x64 os, it being Windows 10.

FYI. I don't have it, either. The game installed and ran, though.

Had a similiar problem: Installed the game via galaxy, but when I started it, it just told me that it was not installed and no installer was found. I had no Bethesda Softworks key in the registry, it was not created after install. But after creating it manually as described here, the game worked.

Seems to be more common, that the registry entry fails. I also opted for creating a desktop icon: did not happen. Perhaps some scripts do not run?

I am using Windows 7 and as described GOG Galaxy.

Had same problem with Fallout 3.
But I hit the verify/repair button in Galaxy and the problem was solved.
For the record, I forgot to uninstall the Steam version of Fallout 3 until AFTER I had downloaded the game from GOG using Galaxy. That was probably the cause. But, after I had uninstalled the Steam version and did verify/repair, the launcher worked.

So I didn't install with Galaxy. It appears in galaxy but the verify/repair button is grayed out. DO I need to uninstall and reinstall to fix that?

Edit: The button became clickable and it has fixed the problem. Thanks for your help!

I can vouch for this. I simply hit Verify/Repair button and New Vegas started working like a charm then again I too uninstalled my Steam versions of Fallout 3 and New Vegas in favor for GOG versions. I'm just super happy to play Fallout 3 again as it just wasn't working at all via Steam but whatever GOG did its working well here and the loading is super fast too.

Necromancer here, just raising the dead since GOG gave out FONV today, and I'm having this exact issue on Debian. Make sure you run regedit through winetricks if you're using a launcher such as Heroic Launcher. Adding these keys and using the windows file location. For instance I have my Z:/ drive mounted to my linux /. So I had to do Z:/media/name/drive/folder/fallout new vegas/ and it worked. Cool thanks, have a good day.