Suddenly, when I left Dungeon Siege 1, I notice that the GOG Galaxy client says, instead the "Play" button, "Syncing 0%".

What is that, and how may I disable it?

I don't need online sync, I have my own backups.

You can either disable cloud saves globally in the Galaxy options or disable it on a game-by-game basis by going into the menu on the game page and selecting Manage Installation > Configure.

Alternatively load the game exe directly...

Though you'd have to find the game folder, and that's so much work for the younger generation.

In Manage Installation > Configure says:

Cloud saves: "Cloud Saves are disabled in GOG Galaxy settings."

The only thing I have done extra is to add a new Launch Parameter to not run the intros with "nointro=true".

Well that suggests you've already disabled them at some point in the past.

Yes, and that is my question, why am I seeing "Syncing 0%", instead "Play" few seconds after closing that particular program. It is Dungeon Siege 1 only...

Edit 1: I must add that I'm playing with the expansion Legends of Aranna, not available for sale but downloaded from a post in Steam easy to find. And with no intros as I said.

Edit 2: and changed its ugly game icon, and with some mods for skins... too many changes lol! (but I play almost all my games like this, only this one is "syncing at the end").

You could also just uninstall Galaxy and use the offline installers - as long as those still exist.

Yes, that is how I've been playing my entire life. I just want to make the Galaxy client work with this game as with the rest. Just trying it work.

That is indeed mysterious. I would suggest going into the global settings, turning cloud saves on and then off again just in case the setting is bugged in some weird way. As others have said, if you can't get it to work then I'd just suggest running the game directly.

Yes, I tried, it didn't work. I think I should have asked it in the Galaxy section, I'll ask it there. Thank you anyway.

Edit: Ahhhh I bought this game also on Steam... maybe it is syncing with that??? But I'm playing the GOG version, never installed the Steam one.

Edit: Checking the settings, in integrations, I haven't other accounts connected. Tried once with my Path of Exile account and desync the same day (for security fears, I think...).