-dx11
Seems like this game plays on dx12 by default and it crashes on startup, adding -dx11 fixes everything and works without any problem.
I didn't tested coop or pvp since I couldn't find anyone playing it, but the main game it's very playable.
You can even enable ray traced reflections, though I wouldn't recommend it as the Steam Deck wasn't designed to handle ray tracing of any kind. The only problem I had was HDR. For whatever reason, the option remains greyed-out in the settings. Otherwise, the game runs beautifully and looks rather stunning at 30 FPS.
I just didn't try MP cuz as you can see on SteamDB, the game's pretty much dead, even with crossplay enabled and the devs' regular live streams.
It worked out of the box after selecting Proton GE from the compatibility list.
-dx11
it won't launch by default, but using -dx11 makes it run just fine
