I also tried running Pathologic Classic HD through Proton and while it shows a black screen for 2 seconds after launchingit then crashes. The Steam AppID of the game is 384110. I added PROTON_LOG=1 %command% to the game's launch options and got the folloiwjng log:

steam-384110.log

I have checked whether there are updates for my system available and I am up to date

System Information:

Distro: Solus

GPU: RX 580 8GB

Driver/LLVM version: Mesa 18.3.2

Kernel version: 4.20.3-108.current

Proton version: 3.16-4

https://gist.github.com/Simmonz/d2112ca84cdc09a2a5f419ddc3f19c40

288.866:0024:0025:warn:debugstr:OutputDebugStringA "Sat Sep 01 11:05:58 2018: Renderer: Pixel shader error(debug.hlsl(builtin):): error X3501: 'main': entrypoint not found\n\r\n"

Should be the missing HLSL compiler support in wine. Native d3dcompiler dlls may fix this.