I took a screen pic of GKNOVA6 with the second-to-last image on the screen in the middle selected. I took this into Paint.NET quickly and inverted it. I noticed the blue screen inverted is pretty much the exact color of blood, which the zombies game mode is all about. I zoomed to about 400% (I suggest you do the same while reading this) and noticed the middle screen made out two claw-liked images in the middle of the screen. Now look to the second-to-the top right screen. If you look closely, the darkness in the picture seems to make out a human head, starting for the shoulder. Could this be a distorted zombie image?
Also, if you flip the image horizontally (too lazy to post another picture, lol), the numbers next to the screen on the middle can be made into letters. I read it "BAO AaT." Maybe that will be relevant to any decoders?