I've recently bought Guards, because I really like turn-based games.

But the game did not start on my system (it just exited without any error message), and the developer sadly had no clue how to fix it.

So I investigated the issue, and found a fix, which might also help for other Unity-based games.

1) take a look at the Player.log. It is located here:

/home/yourname/.config/unity3d/Battlecruiser/Guards 3D

Mine said something like

invalid resolution: 11x1000 (some bogus numbers here)

so I opened the file prefs and saw this:

pref name="Screenmanager Is Fullscreen mode" type="int">0
pref name="Screenmanager Resolution Height" type="int">11
pref name="Screenmanager Resolution Width" type="int">1000

which is clearly NOT my screen resolution and changed it to:

pref name="Screenmanager Is Fullscreen mode" type="int">1
pref name="Screenmanager Resolution Height" type="int">1080
pref name="Screenmanager Resolution Width" type="int">1920

Also I've had to change the startup options in the Steam-Client, and then the game started and worked.