Are you using the itch app? I don't think it works on that.
It may be something to do with the default screen res - which is 1280x800 if your system allows. Can you try editing the Data/Options file and changing the FULLSCREEN flag to either 0 (scale-able window) or 2 (normal window). If an ini file wasn't created let me know via email@example.com and I'll send you one to try.