Here you can see that there are normally artifacts at the corners (enlarge the pic to original size by clicking on it). I fixed it by giving the game a not visible 1px border for left and right and 20px at top and bottom. You can disable the visible 'cinematic' border by changing the second number (20) in float() after '#define border_width' to 1! Don't change it to 0 or disable Border, otherwise the Artifacts are there again...