Doesn't fully close in Steam when exiting the game, but you can very painlessly and easily force close it via Steam's library after exiting. Unsure of any fixes for this. Otherwise my launch params squeeze a lot of performance out of the game, I'm able to play on max settings and get at least 60fps out of the game, at most who knows, I cap it at my monitor's refresh rate (165fps/hz) but I do hit that framerate on occasion, not counting loading screens. The game has a history of completely destroying the Linux experience though, so be warned that this info may be outdated by the time you read it. Generally though, Proton Experimental (bleeding-edge) and Proton Hotfix have both been very helpful in getting people in matches when the game is in a "broken" state, so if you find the game entirely unplayable, try switching to those versionf of Proton and give it a try!