Unfortunately the game doesn't work in fullscreen mode and only works in windowed mode, so you can either try play windowed mode but it might look a little small, or you could try using 1920 x 1200 which should make the game window nearly fill the screen while still keeping pixel consistency.
I would have tried to make it full screen compatable but couldn't really due to the the time limit
I just made a 1440p friendly version of the app that should fill most of the screen and work much better