Tim kindly got in touch to provide some additional information on this, which may be of use to others using Linux. Thanks Tim! See below:
I consider the main culprit being Dell. They managed to build a screen which comes with a build-in overscan of about 3-4 pixels (the pixels are actually below the plastic frame) which might look nice for watching movies, yet for Cinnamon with its hard-to-use tiny scrollbars,you can't even see them for maximized windows. The solution is as software underscan:
What I did not realize at first is that this does not only resizes the desktop, it tells 3822x2149 as screen resolution to every application that's asking. I used the same trick earlier to get the game running in 3200x2048. That, however, did not open up the resolution. However, it's possible to switch the game to 3200x2048 windowed in-game and then it comes up without graphics error in higher resolutions. Afterwards, I was able to start it in 3280x2180. Setting the game to this resolution, however, is only possible without the underscan. Also, setting the game to 3280x2180 and afterwards re-enabling the underscan makes the game automatically reset to 3200x2028, and the graphics error re-appear.
To subsum, I haven't tried, but for people who are overwhelmed by this story, deleting the settings file actually does solve the problem if, and only if, any underscan settings are removed for good before starting the game for the first time afterwards. I am now able to freely set the resolution, however, I have to disable underscan to play.
