Niautanor: Tested on Arch Linux and in an Ubuntu 16.04 LTS live session.

I am using an AMD Radeon R9 380 with the open source driver (amdgpu).

Please let me know if I can provide any more information to fix this.

Niautanor: The article that you linked does not explain how to switch to Radeon from amdgpu and my own research didn't yield any results either.

It probably wouldn't have been a good idea anyway since radeon seems to be geared towards older hardware that amdgpu does not support (at least from my understanding).

Anyway, I also came across this thread (https://steamcommunity.com/app/269650/discussions/2/365163686043604822/) in the steam forums for the game where someone reported that the issue was fixed in a beta release that seems to be available on steam.

Do you know when/if this new version will be available on GoG?