Hi Jonathan, thank you, I am glad you like the game :)
The game is a 16 bit looking game (the original I made on 2015 for msx2). So the resolution is fixed. You can exit full screen with alt+enter to play at a more friendly resolution in window mode, or you can press the 1 key on the keyboard (not the numeric pad, but the 1 above the Q) to switch scanlines on and off.
Regarding the blur, I am not sure what blur you are talking about. There should not be any blur. Perhaps your graphics card is using a blur to scale the image to full screen?