I started the game up and pressed the windows key to do something on my second monitor very shortly after the game started but before it had opened the window. Upon maximizing the game it only displayed the top 1/4 of the screen (yet still taking up the full monitor). My main monitor I play the game at is 3840x2160 pixels but I play the game at 1920x1080 on that monitor. I do not play the game windowed but fullscreen.