The earliest edition of Space Invaders was a cocktail table version and came only in black and white. At the time the arcade classic made the jump from Japan to the United States, it was redesigned into an upright filing cabinet; Part of this conversion included adding color to the display.
Since color screens were expensive and the original game did not actually support color codes, American designers at Midway Games became creative. To add more eye conflict to the simplified game, they chose to use a mirror bounce display. The CRT was actually in the cabinet behind the game controls against straight up to the ceiling and then bounced off a semi-reflecting mirror towards the viewer. By adding cellophane over CRT, the illusion of color was created (in this case green and orange). In addition to cellophane, the depth of the gig was increased by placing space artworks behind the semi-opaque mirror to display graphics that the gaming computer itself could not display.
In the picture above you can see how the CRT output was not only colored (with bands of green, yellow, orange and pink cellophane with this model), but was also reflected on a painting of a city against a fiery sky. It would be well over a decade after Space Invaders were released before arcade games could even come close to copying the painted background. Early editions of the game were enhanced with.
The stylish design choice was a blow and excelled the game. At the end of the Space Invader's production run, both American and Japanese cabinets used cellophane and image behind-mirror tricks.