Actually, I think Pacman (or Puckman, in this case

) would be something more like what I have below. I did this in Photoshop. I boosted the brightness slightly on the gameplay image so the background isn't completely black (to make the darker burn-in areas visible). I took the
negative of the burn-in image, and added it as a multiply layer with an opacity of about 30%. The result is subtle (as it should be), but it's there, and I think would be more effective in actual, moving gameplay.
Note that the burn-in
is colored. It's just that it's a negative, and it's used to multiply the display colors. I believe this is the way burn-in would work on a real color monitor, since I think the red, green, and blue phosphor elements would suffer the effects of burn-in independently. For example, pixels that are constantly bright red in attract mode would have the red elements weakened, but the green and blue elements would be uneffected. During gameplay, if something white is shown there (white = full red + full green + full blue), it would show as white (red + green + blue), but with somewhat lessened red, so it would be white with a slight cyan (green + blue) tint.