This happens with all of AKABUR's games.  I open them, press fullscreen and it zooms in too much.

I'm guessing you were able to solve this. Usually it's the windows' zoom function that's causing it.

 The recommended setting for "large" resolutions like 1920x1080 is 150%   "zoom".   Seems, older renpy can not do that correctly. 

While this can be fixed by going temporarily    to 100% for playing the game, it messes up the dpi of the mouse, though mouse is not needed for this game.