
When using heroic with steam runtime, please kill all steam processes and all gpu processes before playing. This game is sensitive for it.
steam runtime
Slow loading. If steam is running, the game was unplayable. Kill all steam and other GPU processes before launching.
No special options used, besides of steam runtime and ProtonGE.

Essentially perfect, and performance was better than expected as well!
At some point midway through my playthrough, the game launched into windowed mode for some reason, but since it was still at my desktop's resolution, the bottom part of the screen was cut off. This made it impossible to click on the apply button in the settings screen, thus rendering me unable to put the game back into fullscreen mode. There's probably some settings file somewhere that I didn't immediately find, so I just used gamescope
to start Steam in a 800x600 screen so that the game opened at that resolution as well, and I was able to fix the issue. Never had the issue again.
Aside from the windowing issue I experienced, there's not much to say here. During my 20 hours or so I had absolutely zero issues, and the game played very nicely. I had zero issue running this at a super stable 100fps at 3440x1440 with Max details (though I admittedly have pretty overpowered hardware). I gave it a short go on my laptop as well, where I was also able to keep an super steady 60fps going.

excellent performance!
Works beautifully AND it's a great game. Win win
I'm currently having to play it on Windows because of the serious performance issues when running with Proton
Really bad performance (even when using Proton Experimental or GE). On Windows: 1440p at stable fps with Max graphics settings; on Linux with Proton: persistent stuttering and slowness on 1080p on Medium graphics settings.
Movies won't play on standard Proton
It just worked straight out of the box

it seems to work fine with experimental and GE
Game's seems working perfectly with Proton Experimental.
Other Proton versions gave me FPS issues on map and during fights after a cutscene, solved reloading/restarting the game
Game automatically switching to windowed with the bottom cut off.
You require Proton-7.0rc6-GE-1to run this. Just google the GE Proton version and you will find the Github download. Check github for install instructions. It is very simple.
Couldn't get it working on EndeavourOS
Game crashes on load. Entirely borked for me.

Lock to 40fps
Under default Proton games works but in game movies are bugged. Under proton experimental video works but game freezes on load a new game. Under Proton 7.0rc6-GE-1 game works without an issue so force steam deck to use it. On max settings game runs in 45-60fps so I locked it to 40.

Black screen then no signal after some time.
PROTON_USE_WINED3D=1 %command%
1603141982 proton-5.0-10b

Loading screen then Steam crashes.
PROTON_USE_WINED3D=1 %command%
1603141982 proton-5.0-10b

The game itself runs out of the box with stable Proton. But there are some cutscenes which are being rendered wrong (all purple, broken). Up-to-date GE-Proton didn't help, but Proton-6.21-GE-2 worked for me. No further issues with the game.

Nearly all good with Proton 7
some pink screens here and there, and few textures glitching
Played the Free Beta of the game. Few graphical imperfections happen from time to times. They do not prevent you from having a good time with this good game.
None
Some static images show as a rainbow effect. Does not affect gameplay.
Works with Steam defaults, but not with GE (first game that's ever happened for me!) Has some room for improvement, but still works well.