So, anyone ever encounter this problem ? The screen has random black areas appear on it randomly, and there's a black trail left wherever gabriel walks. The same happens with the mouse. It leaves black boxes on the screen. Some parts of the visible graphics also flicker. Practicaly makes the game unplayable.

Dosent matter what settings I use ingame, the result is still the same. I'm on Win10 with the latest Nvidia drivers (no forced antialiasing or anything like that enabled in settings). Every other GoG game I own works flawlessly, but this one has me stumped :/

Any ideas ?

Did you try out my DX11 fix? https://www.gog.com/forum/gabriel_knight_series/gk3_1080p_solution_found_d3d11_only

Your fix seems to work like a charm. It's "almost" like playing a remastered edition of the game. Neat. :D