It seemed to be CPU bottlenecked which is strange given that my (albeit weak) laptop cpu is well above the minimum requirements. Although I'm unsure if this is a problem with the minimum requirements, or proton, or just the game as a whole.
Demo run perfectly
the multiplayer breaks sometimes in the demo, but no linux related problems
Demo - Ran fine with default settings
Everything ran fine. Smooth frame rate and game seems fun from the demo
Demo works great (0.1.32C)
The game is not out yet, but I played the demo
Once I found a working Proton version and got past initial graphical weirdness, the game was perfectly playable.
Had to tweak video settings at the beginning, and that was hard to do until I got to a good resolution.
Windowed mode didn't seem to work correctly, and I couldn't switch the fullscreen to my monitor instead of the laptop display.
I turned off the Steam Overlay while in-game.
This report is for the pre-alpha demo version of the game. I did have to tinker with the Proton version and graphical settings. It was very minor tinkering, though.