Hello,
I've written a little script for PlayOnLinux to run the game on Linux. You can find it here:
https://www.playonlinux.com/en/app-2321-GOGcom__Gabriel_Knight_1_Sins_of_the_Fathers__20th_anniversary_edition.html
If some of you can try it, could you tell me if everything's OK? On my computer, with openSUSE 13.2, the game runs perfectly. It can bring some new players, maybe. ;)