

Works great

PROTON_USE_D9VK=1 obs-gamecapture gamescope -f -W 1920 -H 1080 -- gamemoderun %command%
Unlocked the 62 FPS cap inside /SteamLibrary/steamapps/common/Viscera/UDKGame/Config/UDKEngine.ini > MaxSmoothedFrameRate=240

PROTON_USE_D9VK=1 %command%
Launc as 64bit

Nothing serious
Cursor is slow in main menu but works great in game
Worked perfectly out of the box, even faster and more stable than windows, with the same graphical settings.
Works great after enabling D9VK, getting More Performance Than Windows. Also limit your FPS or you'll have screen tearing
DXVK_FRAME_RATE=60 PROTON_USE_D9VK=1 gamemoderun prime-run %command%

After tinkering to add dx9 support and figuring out what proton version it worked perfectly
PROTON_USE_D9VK=1 %command%
Was a bit unstable and froze up my entire system when launching from proton experimental or 8 on 64-bit but swapping to 7 made it work perfectly so while frustrating to figure out I am glad I got it working. this was the last game I was expecting to have an issue with lmao

gamemoderun %command%
Had some ghost props, no idea if it was a problem of the game or the connection

Worked seamlessly with Steam Invites / Join
The game runs just like in my Windows partition without any additional configuration, the people complaining about performance probably never played on Windows, it runs like shit there too.
Singleplayer worked flawlessly ootb, perfect performance on max settings, didn't try multiplayer.

in windowed mode, the cursor in the menus did not line up with the cursor in the OS, but the problem went away after fullscreening and un-fullscreening.
it runs slowly even at lowest settings, what feels like microstutters / random frames taking way longer than expected.
happy I can play it at all haha
Runs like native
Local Multiplayer and split screen works like a charm
Works fine out of box.
Sometimes the game refuses to let you join games, but this is actually a long standing issue with the game in general, not a Linux/Proton issue.
Works fine out of the box. It's a demanding, unoptimized piece of shit game though, and networking really sucks. Still a fun game.
gamemoderun %command%
you will suffer
crashes a few seconds after getting in the main menu
Tried with various Proton versions, including glorious eggroll, and with env variables suggested in other comments such as PROTON_USE_D9VK=1 - no chance.
splash screen, unreal video, runestorm video, main menu, 5 seconds (in which you are free to do whatever), crash.
Slight performance issues, otherwise good to go.
Occasional noticeable FPS drops while there were none on Windows
Allowing Steam to process Vulkan shaders first had a noticeable improvement in performance.
No issues found
When there are a lot of decals on the map the game slows down slightly, which was not the case on Windows.
I'm not sure if it has to do with running the Flatpak version of Steam or a firewall issue, but I was able to connect to my friend's session while he couldn't.
You have a great gaming experience and practically forget that you are playing from Linux.
Set right stick response curve to "relaxed"
Changed physics to High, lowered lighting/shadow effects
Some text may be difficult to read for some
Occasional frame drops in some areas
Recommend changing some gamepad settings to make walking/slower movements easier to do when carrying physics objects.
Works out of the box even in multiplayer
Runs well, multiplayer works.
Download and Play

Loving the game and so glad that I could play it on Linux. Slimey (and bloody) yet oddly satisfying
Walking near the furnace tanks fps, and infrequently had walls and objects taking a sec to load in when I turn around. Likely my computers capabilities and not a proton issue.
When running with more recent proton builds, I can only get to main menu and have <1 fps and cannot do anything. Running on an old build (Proton 4-11-13) it became playable
Game exactly like on windows, even for the buggy physics
Game starts up to the small splash screen, then crashes.
Better performance than I ever had on windows
Works out of the box. Did not experience performance slowdowns like my Windows friends. Runs perfectly if not better than Windows.
Works perfectly fine.
I did not test multiplayer.
Huge maps from the workshop crash the game when trying to load them
A few slight lag spikes
Loading huge maps from workshop crashes the game

Works perfectly out of the box, but the editor doesn't launch
As on Windows: To improve the performance set bSmoothFrameRate to FALSE in $HOME/.steam/steam/steamapps/common/Viscera\ Cleanup\ Detail\ Shadow\ Warrior/Engine/Config/BaseEngine.ini.
Performance was slightly worse than on windows
Ran slightly worse than used to on windows

Works perfectly out of the box
As on Windows: To improve the performance set bSmoothFrameRate to FALSE in $HOME/.steam/steam/steamapps/common/Viscera/Engine/Config/BaseEngine.ini.