
Works great!
There are some error messages I get from Unity when going between menus which I have to dismiss but it doesn't effect gameplay at all.
Perfect out of the box

Works out of the box.
The game attempts to play MS-Windows-compatible videos in the background of the menu, but this doesn't work for me. You can simply dismiss the error message and its log. This issue does not occur during gameplay.

PROTON_USE_WINED3D=1
Other tinker suggestions did not work but this worked without issue

Plays quite well on Steam Deck although I do like to add a bluetooth mouse and keyboard where possible.
Mapped shift, alt, and ctrl keys to back grip buttons.
Text is pretty small on the Steam Deck display. Worst parts are tips on loading screens. Otherwise most other cases are still legible.

Older builds would occationally crash, but that seems to be resolved in newer builds
%100 of my play time is in linux
Nebulous is playable 100% but the performance is not the best but not annoying. Es jugable al 100% pero el rendimiento no es el mejor
The game is 100% playable but don't expect good performance. El juego es jugable al 100% pero el rendimiento no es el mejor.
gamemoderun %command%
WINE_DO_NOT_CREATE_DXGI_DEVICE_MANAGER=1 mangohud %command% -window-mode borderless
Alt-tabbing with fullscreen works fine but using windowed mode causes the game to have a black scren and needs to be terminated.
Intermittent crashes mid-game
WINE_DO_NOT_CREATE_DXGI_DEVICE_MANAGER=1 %command% -window-mode borderless
Seemed capped at 40 FPS
Sometimes would timeout but that could just be the host
Could not regain fullscreen after Alt-Tab
Mid-match, game completely froze and dropped from the server
Unsure if the previous crash was related to multiplayer or graphics.

Just works
Tutorials all seem to work fine. Haven't tested campaign/skirmish/multiplayer.
Runs stable / without crashes, perf is on the lower end (might be due to unity / early access). Fullscreen issue could be fixed easily.
WINE_DO_NOT_CREATE_DXGI_DEVICE_MANAGER=1 gamemoderun %command% -window-mode borderless
Game uses exclusive fullscreen by default, causing a black screen when going to the desktop and back into the game.
This can be fixed by passing using "%command% -window-mode borderless" which forces the unity player to use borderless windowing instead.
In larger battles the framerate drops to around 25 FPS even though DXVK_HUD only reports ~25% GPU utilization, I wasn't able to try it on windows but this might well be an issue with the game simply being unoptimized due to early access (and using unity in general) given that even on "Very Low" Graphics Settings the Framerate remains unaffected.
gamemoderun %command%
Crash occurred shortly into the second tutorial
Game crashes after a short time, and the dev console frequently pops up with various errors. Not currently playable.
gamemoderun %command%
Could not reaquire game after alt-tab
Game could not reacquire focus in fullscreen after losing it, such as with Alt-Tab. Windowed mode worked fine.
Main menu background video does not play properly
Doen't go past the initial loading screen
gamemoderun %command%
Once the loading bar reaches a certain point the game would freeze and eventually crash. My theory is that my low-end pc just couldn't handle the game (even though it meets the minimum requirements). I tried to run it with proton 7.1-GE-2 and Proton-7.2-GE-2, both ended up in a crash (I testet it like 20 times to make sure that it really doesn't work). I refunded it for now untill i have a better pc. Quite a bummer because the game looks really fun. But judging from the other reviews it should work out of the box for people with a decent pc.

Silk smooth & low latency!
Like most unity games this one works like a charm!
Even using an older GPU that's not officially supported by the game I had no trouble running it.
Even running on a GPU that is not officially supported I've had no issues at all running this game with Proton
Proton-7.2-GE-2 GloriousEggroll
Using glorious eggroll 7.2-2, no issues, 6+ hours with 0 crashes or bugs. I tried with the default proton, the background cinematic did not load properly, others have said the rest of the game is fine though.
Works Great! The only issue i found is that the main screen menu background is not working properly, but it's far away from being a problem.

The main menu will have a test pattern on it, due to normal proton not having the mf codecs. I used Proton-7.1-GE-2 and that cleared it right up.
Proton-7.1-GE-2
Extra modification: I used gamemoderun %command%