I installed the game on my Ubuntu 20.04 and it launches.

But on the first screen, I can move the mouse but click has no effect.

I also tried with the keyboard but nothing happen. Any idea ? Did I miss some install step before installing the game itself?

I've got the same problem on Ubuntu 18.04. What I'm seeing is clearly an in-game mouse cursor, so it's not as if it's impossible to interact with the game: it appears to recognise that the mouse is being moved, at least. It's just that (as TitiMoby says) nothing happens when I click any of the options.

I also tried plugging in a gamepad just in case that was an option, but no luck there either. Please do let me know if you ever sort this. It looks like a neat game, and I might try seeing if I can get the Windows version to run in WINE in the meantime.

I also tried without success to plug a gamepad :)

I'll give a shot with Lutris but it seems to be so close to be running natively

Stumbled across this while troubleshooting the same issue.  I got things to work by forcing the use of "Proton Experimental" under "Compatibility" in the Steam properties for the game (the gear icon).