Hey, thanks for the kind comment!
To get that look we render the game at 640x360 and then upscale the image with nearest neighbor. You can do that simply by setting the window size in the project settings and setting the resize behavior to "viewport". After that, it's mostly a matter of artstyle, we chose a simple artstyle because Arkatein is new to blender and it lens itself well to the pixelated look.