It's playable from the beginning from the DEMO to the end of it, thought not without it's issues:
Frame rate drop (thought haven't tested this game on Windows so it may not be Proton's fault)
Fullscreen is a chore to make it work correctly (Sometimes it shows a cropped part of the game's display in the top-left side of the screen, sometimes it's not even the correct resolution) (It's better to play the game windowed)
Apparently, the game suppresses other application's sounds but I wasn't able to verify this
Reproduction
With .NET and XNA installed, start the game and try to set fullscreen on from the game's options.
Compatibility Report
System Information
I confirm:
steam-383570.log
(The log is a complete DEMO run of the game)
Symptoms
Installed .NET Framework 4.7.2 using this guide and Installed Microsoft XNA Framework from: https://www.microsoft.com/en-us/download/details.aspx?id=20914 (Using the GUI installer)
It's playable from the beginning from the DEMO to the end of it, thought not without it's issues:
Reproduction
With .NET and XNA installed, start the game and try to set fullscreen on from the game's options.