Yes I tried to activate in settings menu, nothing happen, so I restarted the game, and the same.
I don't know, maybe because my screen does not have other resolutions available than 2560x1440. And the game tries to "fullscreen" with a lower res.
Does the new version underwater suffers the same problem ? It seems more "polished" than Tachyon on your screenshots.
Can we start the game with resolution parameter/argument in command line ?