MadalinStroe: I just tried this out a couple of moments ago, and the behavior is exactly repeatable on my end too. I used Galaxy to install the game.
EDIT: Here is the fix: 1. From the Galaxy client I used the "More" drop down button, and selected the "Settings" option.
2. I UN-checked the "display notifications and access GOG Galaxy when in-game" option(which is enabled by default).
3. The game runs correctly after that.
Thanks for your advice! I tried, and worked. :)
My only problem was, that I tried it before installation, and than I didn't found "display notification ...". I tried to install, and after I found what you wrote. :)