🤑 Indie game store🙌 Free games😂 Fun games😨 Horror games
👷 Game development🎨 Assets📚 Comics
🎉 Sales🎁 Bundles
(Edited 2 times)

Let me try to find a solution for you. I will get back to you.

EDIT:
First off, you can try to hold the alt-key when starting the game. A resolution dialog should pop up.

Otherwise hat you could try (while we try to get the grip on a more definite solution) is try to use the following command line arguments:
-screen-fullscreen
Override the default full-screen state. This must be 0 or 1.
-screen-height
Override the default screen height. This must be an integer from a supported resolution (e.g. 720).
-screen-width
Override the default screen width. This must be an integer from a supported resolution (e.g. 1280).

So run it with -screen-fullscreen 0 -screen-height 720 -screen-width 1280

If you are not familiar with command line options, let me know.

Thanks! I forgot about alt for unity games!