Unless I'm missing it, although there are not many places I can see to look in the first place, I do not see an option to opt out individual games from the auto-update feature.

Most of the time, I do prefer the auto-update. There are instances where leaving this on universally will cause on update for a game that I do not want updated. NWN2 for example, requires me to use a community made fix (Client Extension) so I don't get terrible micro-stutter while playing. The first thing GOG Galaxy 2.0 did upon installation was give me a 356mb update for NWN2 that at this point I'm not sure it will still work properly. It's not a big deal fixing again, but it does force me to turn off universal auto-update so it doesn't happen again. I otherwise would prefer to have this option turned on.

Some form of option on a per-game basis is needed to opt out those games that you don't want auto-updated.

Thanks.

Open the game and select the icon right to the play button->manage installation->configure (picture 1)

This window will be opened (picture 2)

Select the installation tab and untick the auto update. (picture 3)

Great ty! Glad I missed that.