I recently bought Ziggurat and installed Version 2.0.0.2 from the shellscript installer. Launcher and intro work fine.

In the main menu, I went to settings and noticed that suddenly the back button did not work (first occurred in the sound menu). Neither did ESC. I quit the game via Alt+F4.

I started again, avoiding the sound menu. After inverting Y-axis, I could not go back, again. Alt+F4.

Starting again, I could not hit any button in the menu. Alt+F4.

The config directory (~/.config/unity3d/Milkstone Studios/Ziggurat) at this point contained:

global_config.xml
Player.log
prefs

I tried deleting the config files, to see if I could start a vanilla game. To no avail.

This is my current status: I cannot click buttons or launch the game.

After reading the gog game card and installing all the libsdl2-libraries from the Ubuntu Software Center, the game works with no problems at all. :-)

Sorry to bother you.

PS: I cannot figure out how to marks this as FIXED.

Weird. So you're not supposed to find out for yourself …

I took the liberty of marking yours to get this topic SOLVED. Thanks for the info.