What monitor resolution did you play on and did you play in the broswer or download?
The game window is made to be 1024 by 1024 so if you're playing on a resolution lower than that or if you go fullscreen in the app it may make the game look wierd.
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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