It's a native linux port; no Proton.
Trying this again, hello @daasuharo, this should be also be brought to the game dev's attention.
Okay, I sent out an email to them. I can add responses from them here if you want.
Closing because this is/was an issue with a third party game and the reporting user has turned into a ghost.
Nothing extracted yet.
Your system information
Please describe your issue in as much detail as possible:
Under Windows 10 the game has native support for DS4 controllers that works but doesn't under my linux distro. It detects it as an unknown wireless controller with no inputs from it working.
Steps for reproducing this issue: