Surprisingly enough, NONE of the tweaks mentioned on this page worked for my rig. Some versions of Proton still gave me black screen on launch despite installing all the dlls, newer versions lauched the game just fine but the shaders were borked beyond belief. Surprisingly enough, some lauch options (namely -nomovies) caused the game to straight up crash on me. In desperation I've turned to the native Linux runtime option, and... Yeah, it worked just fine. Once in a while there's some minor audio stutter, but apart from that the game runs fine. No multiplayer with Windows users, I guess. No big deal.