ThomasJChoi: Question is the title, basically.
I'm having a few issues with the regular executable so I decided to try launching it through the Launcher to test some things but the Launcher seems to use the Steam version. Here's a couple of results:
1. Steam not started -> Clicking "Play" starts Steam, launches the Fallout4Launcher.exe from the Steam version.
2. Steam is started -> Clicking "Play" closes the GOG Fallout4Launcher.exe and opens up Steam's Fallout4Launcher.exe.
3. Temporary removal of steam_api64.dll -> Launcher fails to start because it says it can't find steam_api64.dll, so it appears to be a dependency.
I know as a DRM-free version of Fallout, many of you are probably just running the Fallout4.exe executable, so I was just curious if anyone else was using Fallout4Launcher.exe and it exhibited the behavior described above.
That sound like you have the Steam version and the GOG version installed alongside. I think that's the reason the launcher gets confused. I personally removed all traces from the Steam version (uninstalled all mods and de-registered the game in the mod manager, uninstalled the game completely using the Steam uninstall, made a back-up from the save files and deleted the Fallout 4 directory in Documents\My Games completely).
After all that I installed the off-line version (choose another drive for that), and run the installer. The result was a nice clean game and no Steam starting up.