
Text on notes found throughout the game may be hard to read on the Steam Deck's integrated display.
Graphical degradation on game start as assets are loaded. Resolution improves after a few seconds of play.
Game runs without any additional configuration. Both the Steam Deck controls and any attached gamepads work out of the box.

Gave fatal error on launch.

Ran perfectly for over 2 hours.
My co-op partner on Windows had a couple issues. There was about 30 seconds where he could not attack at all.
No complaints. Default Proton and all.
Needed to change controls to gamepad, other than that, works well on default settings!
small annoying issues abound, but its not gonna stop you from generally having a good time
would not scale output properly, fixed with GEproton
slowdowns, low fps compared to playing on windows, bossfight was atrociously bad performance, might be because of EA though
crashed once while discord screensharing
you can play it in window mode with normalt proton, but would highly recommend GEProton for this one
Proton 6.9-GE-1 is mandatory to launch the game, any other version I tried didnt even launch the game.
UE4 Prerequisite installer failed, but game launched fine with D3D11 on second attempt
Choose D3D11 when starting the game, the UE4 pre requisite will likely fail/wont finish. The game will launch the 2nd time. I've had a couple of random issues with the mouse cursor in the menus (not clicking where the cursor was). Performance isnt great 30-50FPS on average, even with settings lowered to medium.
Barely playable for now.
When selection 1920x1080 on a 2560x1080 display, it does not stretch the screen; you have to select the exact resolution for a satisfatory result
Moving alone!
Works well enough in D3D11 mode.
Only during cutscene.
Default mode would not start or install VC++ library but game runs fine if you select D3D11 from Steam launch window instead of the default mode (Graven).

6.10-GE-1 GloriousEggroll
Only when changing fullscreen/windowed, and resolution.

6.10-GE-1 GloriousEggroll
Only Glorious Eggroll's proton version 6.9/10-GE-x correctly displays videos at this time of writing.
I run a 1440p monitor, but on first bootup it only shows half the menu in a windowed 1080p resolution, while trying to stretch that 1080p across my entire monitor.
my savegame was made under linux. it synced within windows, allowing me to load it there. but when i wanted to play it under linux again, i noticed it didn't sync my savegame made under windows.
initially it ran fine, but after having a savegame it froze in the menu everytime started the game after that first time.

Glorious Egroll's Proton-6.9-GE-1 GloriousEggroll
Glorious Egroll's Proton-6.9-GE-1
The first time the game started it played the 3DRealms logo thing. After that it tried to load the menu, but then dropped to some kind of broken windowed mode. Looked like it was still set in "fullscreen", but rendering only half of the window. Navigating the menu at this point was borked. Clicking menu items did not work, i had to first leftclick, then hit enter to open the options and toggle the correct resolution. However, this might have been an issue with my windowmanager (QTile). The problem did not return after restarting the game.
Overall FPS was around 50ish, but still very playable. Some stuttering/stalling for about 1-half-a-second or so when entering some areas.
I only played for about 1 hour, but overall the game runs fairly smooth. My main issue is with FPS being a bit sluggish in certain areas but still very playable. Haven't played on Windows yet so don't know if the performance is the same. The game is just released on Early access after all.
As others mentioned, the UE4 install complains (after the vcredist stuff), but the game runs after a restart.

Glorious Egroll's Proton-6.9-GE-1
Works flawlessly after redist "install." - UT4 runner says it fails, but the game launches. It is possible to adjust winetricks, and install vcrun2019 into the prefix manually, but this GE Proton allows it (see 6.9-1 patchnotes)

Even keybinding åäö on my swedish keyboard was successful as this is often a common problem to have wasd movement input.
6.9-GE-1 GloriousEggroll
Some areas/game assets are in need of optimizations.
The UE4 prerequisite installer exited with "installation failed" but on a second launch of the game it didn't appear again and the game started up as expected.

I was even able to keybind swedish letters åäö which often are problematic and I need those for wasd movement on dvorak layout.
6.9-GE-1 GloriousEggroll
Some areas are not yet optimized well. GPU utilization is around 50% and CPU even less.
The UE4 prerequisites installation ended with "installation faliure" and then game never started with DX12(default). Upon starting the game again with DX12 (default) no UE4 prerequisites installer was started and the game lanched successfully.
works fine without working cut-scenes on 6.3-4
videos are just tv static but it runs if you select d3d11 as the launch option
Menu starts, black screen after clicking on New Campaign

Intro video broken on stable Proton. Use Proton Experimental (test pattern), or use proton-ge-custom to view cinematics.
6.1-GE-1 GloriousEggroll
Black screen after main menu

Proton fails with Black Screen but wine-staging runs
The game starts using Lutris and adding the game manually, changing the runner to wine-staging-6.0 (system) and also changing to Win7 in winecfg. With this, no black screen at play. The game is playable with this configuration.

Proton-5.11-GE-2-MF GloriousEggroll
Movies require mfplat
(Demo) Very limited display settings, AA off and Shadows Medium for stable 60 FPS
Blackscreen fixed to change prefix for win10 to win7.
Black screen after hitting play on the demo.

Black screen after main menu on demo version.
Screen remains black after starting a new game, sound will continue playing but nothing else happens. Tried with both standard (I assume D3D12) version and D3D11 version.