I've been *TRYING* to play Heroes of Hammerwatch on co-op.

Every time I unlock an achievement the GOG Galaxy overlay automatically opens and I am unable to close it. Shift-Tab doesn't do anything. I am unable to click any of the buttons on the overlay and only fix is to just ALT-F4.

Before I ALT-F4, all my inputs get into the game. My character moves on the screen, shoots etc. (I asked about this from my co-cop partner) but as I am unable to see anything except the overlay and can't un-toggle the overlay I am unable to continue playing and need to ALT-F4 and restart.

This is really frustrating. First I thought it was due to some settings on notifications or the overlay, but this continues to happen even after I disabled ALL the notifications. Everything is now set at "-" but still this continues to happen.

I am forced to keep the overlay active as it's the only way to join the game my partner is hosting.
We also tried me hosting the game and everything works just fine then, except the problem then happens with my partner.

She has also disabled all notifications. I really don't know if this is GOG Galaxy's fault or the game's.

Nevertheless this makes the game unplayable and very unpleasant.

The only thing that worked for us was disabling the achievements altogether.
You won't get all of the earned ones while the setting is disabled. Though, the overlay doesn't interrupt the game. Necessary evil until the fix is out, I guess.

That's a really bad workaround for a platform as big as GoG is. Tried that and worked for me, but I don't want to disable achievements