Every time I download and install any GOG game from the store directly just because I don't feel like launching Galaxy, the damn client keeps launching and searching for any game that I have installed this way. It's become rather annoying and makes me wonder how "optional" Galaxy truly is. Is there a way to stop it from doing it? Or am I gonna have to uninstall Galaxy at this point to play truly DRM-free games?

The client isn't DRM, so no matter how you slice it, you still have DRM free games.

Are you using the Galaxy installers instead of the classic installers?

What do you mean by "keeps launching and searching"? Does that happen when you click to play a game via the shortcut? If so that is just a simple change to the shortcut itself and can be easily bypassed by launching directly from the game exe or creating a new shortcut to the games exe file. Galaxy will pick up on games automatically that include Galaxy related files but should not launch automatically unless the shortcut is set to launch Galaxy first.

GOG made this change because a lot of users don't understand Galaxy has to be running for certain Galaxy features to work. So if the game uses Galaxy features (like achievements or cloud saves) GOG has modifed the shortcut for some games to launch Galaxy if Galaxy is installed when you go to play. But as I said you can easily bypass this change.

As Paladin said, Galaxy isn't DRM in any way. The files you get from the offline installers are the same files you get via Galaxy (except for maybe a few rare circumstances). There is no DRM in files installed via Galaxy compared to the files installed via offline installer.

I'm using the classic installers. What I mean is that every time I finish installing a game, Galaxy detects it, boots up, downloads it's dozens upon dozens of updates that has come out since the last time I updated the client, then lets me play the game. It's mighty annoying. It may not be DRM, and it may be bypassed easily, but it sure as hell doesn't make the client feel any optional and is far less convenient than Steam.

What I'm asking is if there's any way to stop Galaxy from doing this. If not, I'll just uninstall the client since I only ever used it for The Witcher games and to help beta-test it when it first came out.

Just tried it with Shadowrun Dragonfall and Shadowrun Hong Kong. Exited Galaxy completely, ran the classic installers I have downloaded and let them finish installing. Clicked Launch on Dragonfall's installer end screen, which did pop up Galaxy, clicked exit on Hong Kong's installer end screen, which did not pop up Galaxy. Both desktop shortcuts were non-Galaxy ones (until Galaxy updates them? unsure), so clicking exit on the installer and using them to run the game didn't execute Galaxy.
Forgot to check the start menu shortcuts before opening Galaxy again, so it is possible that the installer adds Galaxy shortcuts to the start menu.

Feel free to mention what games automatically boot up Galaxy when they finish installing, since I'm also curious about that. But I agree with what BKGaming said, including the uninstalling of Galaxy if it doesn't suit your needs.

They include a launch button on the end screen? I really don't remember that... but I haven't used an installer probably close to a year now. xD

They must be linking Galaxy into the launch button then like they do shortcuts now which launched Galaxy if it is installed. So the solution would be the same as the shortcuts then, exit the installer before launching and check the shortcut before you play. Create one to the exe directly as needed.

Yeah, you can choose 'Exit' or 'Launch'. I've never actually used the 'Launch' option though.

I probably never did either then, which is why I can't remember it. xD

I see. So "Launch" after the installation is done actually launches Galaxy instead of the game, or launches both. Thanks for the help!

GOG should really include a user preference for "I don't want to use Galaxy, please don't pester me again...".

That I say as someone who actually likes the thing and uses it since Alpha...

Why would you have it installed if you don't use it. Are there certain times you continue to want to use it?

I use Galaxy for lots of reasons, the easiest reason is it has my library of games all right there. But why not just uninstall it if you don't like it?