
game defaulted to window mode which impacted performance, changing to full screen resolved all issues

Only tested campaign, worked great
worked great, no tinkering.

options.cfg -fov:95 -motionblurscale:0.0 -noptt
Aim assist messed with the aim, disable it
Windows save doesn't carry over to linux and vice versa (Level/campaign progression, player level and such don't save)
Played with a friend. I was hosting the server and he was on windows, overall it was perfect. Most desyncs happen tho (such as incorrect player position and enemy position) but theyre not that bad and could just be ping issues. We also tried playing on his server and it was perfect too.
Really fun game to play with a friend and it works just like on windows if you are on linux

One time falled from map.

went to options.cfg on the game's folder and deleted "#" on -fov:90 -motionblurscale:0.0 -noptt
The game has heavy mouse acceleration, you can disable on the game settings.
Some frame drops from time to time not matter the graphic settings
Tried coop and the game kicks both players after 2 minutes, probably just a normal problem of the game itself.
Overall it's playable...still F.E.A.R 3 tho, a very mid game.

options.cfg -fov:95 -motionblurscale:0.0 -noptt
If you have issues with the aim (seems off, like as if its mouse acceleration) DISABLE AIM ASSIST. This is the stupidest setting ever and doesn't label it self like a huge issue but it really is one
gamemoderun %command%
gamemoderun %command%
Game runs well out of the box. No tweaks other than gamemode.
unable to load my save from steam cloud. see steam guides on how to edit a save file to unlock everything.
tried coop only with success.
see issues about mouse acceleration
Weird mouse acelleration kind of thing where sometimes the mouse would be super sensitive and other times the mouse would feel very low sensitivity making it very dificult to aim. Seems like the faster you move the mouse the more sensitive it was to that movement.
Not completely unplayable but, not being able to be accurate in any meaningful way makes the game a lot less fun to play.

Works well OOTB. No customization needed.
Servers might be offline - could not find any games to connect to. (Might not be a Linux thing)
No issues to report. Could not connect to multiplayer but it seemed like there just were no other players.

In-game prompts always show keyboard/mouse inputs, even when using a gamepad layout.
Steam Cloud is nominally supported, but not working (nothing is uploaded or downloaded).

I've found that this game works perfectly on my Radeon GFX cards where as it fails to start when using any Nvidia cards ranging from 950 to 1650
Crash on Startup
Shows the splash screen with F.3.A.R and the version number and then quietly quits.
Runs very smoothly with no issues in controller mode besides lacking controller button labels even with controller mode on.
30 FPS limiter
Y axis on mouse does not work at all
Button prompts with controller mode enabled default to keyboard key labels

Smooth 144 Fps on highest settings, no issues whatsoever.
Works great with Proton 7.0 now the DRM problems have been resolved
DXVK_ASYNC=1 %command%
In case you're wondering: No, the cracked EXE won't hurt your ability to play online. I have just finished the co-op campaign on this setup.
Runs like a native Linux game. Very pleasantly surprised

Run smoothly after the installation of Proton Experimental version. You do not need to install any other cracked/patched DRM version.
Experimental

Game runs great out of the box with Proton Experimental with the official Steam client at 4K!
This fixes the DRM issue.

game runs as if native
be aware: game not starting without cracked exe
Game now runs perfectly with the latest steam beta + Proton experimental! No need to use a cracked .exe
Unable to launch even with CEG

After replacing the executable with v.16.0.20.1060 it runs flawlessly to the end.
It's advisable to do a clamav scan on the exe first, for safety's sake. Additionally, all you need to replace is the executable, don't bother with a DLL or anything like that. This clearly doesn't qualify for me as working out of the box; cracked files are shady and there's no reason for me to need to use one aside from conspicuous malfunctioning copy protect code.
"nearly" out of the box
You need replace the main executable with the cracked one, accomplished that, the game runs very well

Replace FEAR3.exe with the cracked version and game will start, which is sad because game was paid...
Replace FEAR3.exe with the cracked one (downloaded from some source :) ) and game will start.
Tried every Proton version out there (including GE-custom), it just won't start. Cracked .exe didn't work either so it's no DRM problem.

Fails to start
Fails to start with all versions of Proton available

Not encouraging, but if you really wanna play it, you have to crack it, then it will work like is native(more than 8 hours played).
Game does not start, no error messag or anything

Still Borked
Tested with Proton 5.0.1, the game still won't launch with the original launcher.
Blocked by DRM - Use cracked exe
Due to DRM , forced to use crack.
DRM issue,need to use a cracked V16.0.20.1060 executable and it work
please tell to developper to change their exe file for run with proton.
DRM problems, the only way to solve it is to replace the original .exe with a cracked one.

Does not start

Game does not start. Shows running in library but nothing happens, then stops showing running after a few seconds.