Atari Cosmos is a prototype game that was pretty much finished, but Atari decided to scrap at the last minute. (Partly (if not mainly) due to the fact that it really does suck as far as a game is concerned. :) They claimed it was 3-D or holographic, when in reality it was just a small grid of LEDs (7x6) with a dual-image hologram used as a background. There were two lights inside of the game shining on the hologram at different angles, and that would cause one of two images to light up (in the case of the Space Invader game, there was a constant background, and when you died an image of an alien shooting you would appear). Eight games were developed (along with the holograms), and all of them were programmed into the base unit. A series of tabs on the 'cartridge' told the base unit which games to play. 6 Cosmos units are known to exist today, and 3 of those 6 are only empty shell mock-ups (although Atari made hundreds of the empty shells, it isn't currently known if these were destroyed/thrown away, or if they are waiting to be found in a warehouse or garage somewhere...). One of the three working prototypes (and at least one of the mock-ups) belongs to Curt Vendel of the Atari Historical Society (these are his pictured, photographs taken during Philly Classic 2001, thanks again Curt for letting us play with this elusive game!). The only other known fully working prototype is still in the hands of a former Atari employee (the third was discovered in January 2010 in a storage facility in the San Francisco area and included one cartridge (Asteroids) (no other Atari stuff was in the storage unit). It was listed on eBay as only partially working, and most of the control buttons were missing. It sold for $7500). If you want more info on this system, check out the Atari Historical Society at www.atarimuseum.com.
Non-working mock-up and box on display at Classic Gaming Expo 2001:
Here's the display from Philly Classic 2001: The top shelf is the empty-shell mock-up, the bottom is the working prototype. The first picture on the backdrop is the first mock-up design for the game, the mock-up actually sitting here is the same one pictured after final modifications were made to it. The square piece next to it is a 'cartridge' shell. There would be a hologram placed in it and a certain number of the 5 openings would be covered to select the game to be played. (That's Doraemon guarding it all in the background... :)
Here's a picture of the light assembly on the bottom and brochure image of the
game:
