

Works well out the box
Good game

Bottom half of screen was heavily artifacted upon initial install.
Game launched fine and started a new game successfully using default Proton. Just like SoC, bottom half of screen had major artifacting. Checking settings, resolution was set to 1080p. Changed it to native 1440p and artifacting was gone. Tested DX10, ran perfectly, no crashes or save corruption.
Tested a couple of random modpacks (Clear Sky Mod Pack 2012, The Warmongers) and everything worked fine. I'll note that in order to make mods work, their gamedata folders had to be purged of any remaining 'Thumbs.db' files leftover from Windows. Open a terminal, navigate to wherever the mod's gamedata folder is and enter:
find -type f -name "Thumbs.db" -exec rm -i {} \;
This also got mods to work in both Shadow Of Chernobyl and Call Of Pripyat. Thank you, ancient r/stalker post. Funny how the buggiest of the trilogy gave me the least trouble. Never change, S.T.A.L.K.E.R.

Installed the Sky Reclamation Project mod.

As long as you force the game to run at higher FPS via Launch options, the game runs perfectly fine, or as good as a game this old can run.
DXVK_FRAME_RATE=144 %command%
The game felt like it was running with below 30fps without extra launch options

Works out of the box, DX10 requires a couple options to be disabled for an enjoyable experience
DXVK_FRAME_RATE=142 %command%
If using DX10, sun rays must be disabled or they will cause heavy artifacting in the lighting. Enabling MSAA, also DX10 specific, will completely break the main menu but you can still navigate it using the arrow keys and Enter. Can be fixed by disabling MSAA with r3_msaa st_opt_off
in the console.
DX10 does work if you want better graphics, but sun rays must be disabled and anti-aliasing will completely break the main menu but you can still navigate it with the arrow keys, so it doesn't bother me too much. No problems otherwise.

Proton works flawlessly and it is a great experience. You can also run it with OpenXray which allows for a NATIVE Linux experience. I build OpenXray with my script and play like that. No need for Proton here.

Made some tweaking for my comfort

Works out of the box
Migrating all games to Linux and so far, Stalker Clear Sky has now been added to that list
Works flawlessly out of the box, however the game has to be in D3D9 mode. Turning on D3D10 or 10.1 lighting causes bad visual artifacts

Once you sort out the keyboard and mouse to controller binds it is a very good experience.
Aiming with the right trackpad is surprisingly nice.

Running it normally works perfectly, some mods (like Atmosfear) needed extra setup with Protontricks.
The Atmosfear mod had some issues, often times the skybox wouldn't render and would just be pitch black. This is probably a proton issue since this didn't happen to me on Windows.
It's a STALKER game.

Works OOTB
did not have issues, but played for a bit.

gamemoderun %command%
needed d3dx9 and vcrun2013 to launch so i can play the ABR Mod
It works, but i need to install some stuff with protontricks (listed above), I used ABR Mod with dx8 and minimum settings.
DXVK_FRAME_RATE=60 %command%

LMDE6, AMD APU 5700G:
The game wasn't starting due to "Your video card doesn't meet game requirements. Pixel shader v1.1 or higher required" error.
To fix it I followed these steps:
- install protontricks (probably winetricks too)
- use terminal to run protontricks GUI: protontricks --gui
There select STALKER: CS -> Select the default wineprefix -> Install a Windows DLL
Select DLLs: d3dx9_31, d3dx9_36, d3dx9_37
After these fixes game works very well, maybe with some minor FPS drops, which aren't very common.
More info at: https://appdb.winehq.org/objectManager.php?sClass=version&iId=34532
X-ray crashes, nothing what wouldn't happen on Winddows.

Works with Lutris but not Proton
PROTON_NO_D3D11=1 %command%
Was unable to launch the game on Ubuntu 22.04.4,Tried all versions of proton including Glorious Eggroll. Tried all launch options that I found other people using. Tried modifying settings in user.ltx in game directory. Gives various errors: "Failed to initialize graphics hardware..." "Your video card doesn't meet game requirements. Pixel shader v1.1 or higher required" " A crash has been detected by BugTrap..."
Finally I was able to launch the game by installing the Windows version of Steam using Lutris then installing and launching the game through there.
The main menu would crash. Enabling "Enhanced Full Dynamic Lighting DirectX 10" in the graphics settings menu fixed that.
I can play reliably using Lutris, however the game launches in a small screen with restricted mouse movements. I work around this by changing parameters in the user.ltx file to: rs_fullscreen off and vid_mode 864x486 each time before launching the game. I can then change the settings back once it is running.

Sometimes I will see a texture of a poster or something bug out, or a texture completely transparent. It's very infrequent enough though and will not hinder game play whatsoever

conclusion
Switched all proton version
before i have an error "Your video card doesn't meet game requirements Pixel Shaders v1.1 or higher required". After install directx libraries using protontricks and using latest proton, - 8 and experimental, i ahving stuck but no have an error. This manipulation fix running S.T.A.L.K.E.R.: Call of Pripyat for me but dont fix S.T.A.L.K.E.R.: Clear Sky. Cry.

had to use a older proton version because the mouse was invisible and stuck which also seem to happen for some windows user. otherwise couple crashes but thats the stalker experience.
PROTON_USE_WINED3D
Older saves on vanilla Xray doesn't works on Openxray engine
Some servers with anticheat enabled doesn't connect
PROTON_USE_WINED3D11=1 %command%
off dynamic lights
little drop fps
The game will start on steam deck only if you enter the start commands
Runs really well out of the box.
Played through all the campaign, did not find any problem.
DXVK_FRAME_RATE=60 %command%
- One very minor graphical detail I noticed was that wires on wired fences were not visible. This was actually a little annoying though I can't confirm that this is a Linux/Wine-only issue.
- Switching over to the DX10 renderer and enabling some of the exclusive features there can give unpredictable or completely broken results. Stick to DX9 and you'll have no issues.
I was able to play through the entire game with almost zero issues, as long as you do two things: stick to the DX9 renderer and install the Sky Reclamation Patch 1.1.4 (don't forget to apply the additional widescreen fix included). This gave me a very stable vanilla game that ran and played very well, no mods are required to enjoy the game like this.
MANGOHUD=1 PULSE_LATENCY_MSEC=60 DXVK_FRAME_RATE=144 %command%
"Your video card doesn't meet game requirements Pixel Shaders v1.1 or higher required"
Changed jump button to [L4]
almost all the text is difficult to make out without looking closely
As soon as you arrive at the junkyard location, the game crashes and often
Everything was played perfectly, but at the location it brought down every 10 minutes the game closes and there is nothing to be done. Maybe you need to install an older version of ProtonGE... but the game is not playable with version 7-41 yet
Mouse would get trapped in the center of the screen on borderless windowed

Slight artifacting in rain in the Cordon, but nowhere else, and even there it wasn't consistent or gamebreaking.
Minor stability issues, but that's to be expected from these games. Had to launch exe with Wine prefix in Lutris to get it to actually launch but after that it was smooth sailing.
I had a little problem whit this particular error upon launching the game: "Your video card doesn't meet game requirements Pixel Shaders v1.1 or higher required"
After a bit of tinkering with my system and updating Nvidia drivers through package manager I was finally able to run this game without any flaws.
"Your video card doesn't meet game requirements Pixel Shaders v1.1 or higher required"
__NV_PRIME_RENDER_OFFLOAD=1 __GLX_VENDOR_LIBRARY_NAME=nvidia %command%

Runs out of the box as long as you don't bump up the graphics settings too high, this caused video issues at the main menu.
This game runs on XRAY engine which is known to be quite unstable, if the game crashes it's most likely the XRAY not Proton.
DXVK_FRAME_RATE=60 %command%
It works perfectly well, but I recommend using DXVK_FRAME_RATE=60 %command% to limit the frames since the engine has no option and does not limit frame rates (not even with vsync on) and will limit out your hardware, no matter how powerful.
Works flawlessly witth Proton 7.0-1
Game starts minimized, I have to manually restore the window (it restores to fullscreen without issues).
I've ran the game both vanilla and with the Sky Reclamation Project without issues on Proton 7.0-1. I remember before you had to force Proton 3.16-9 for it to work without issues, so I'm not sure what changed, but I can now launch it without issues on the latest. If you do get issues booting on the latest, do try 3.16-9 instead.
Works perfectly out of the box
Experienced one crash, but it's not Proton's fault, It's just Clear Sky's "feature" (if you played on the game's initial release date you know what am I talking about) Anyway, apart from that, everything works as intended, no issues found