Sabrinas Fine Collectables have placed an unreleased prototype for an Atari 2600 game known as Peek A Boo up for sale on eBay.
Peek A Boo was developed by Atari in conjunction with Dr. Lee Salk and was intended for very young children to teach them direction, memory, and spatial orientation. The game was scheduled for release in 1984, but never happened.
While the cartridge does have a stick over a label for Pole Position II, it is actually Peek A Boo. To help ease collectors, Sabrinas Fine Collectables has a feedback score of 4,654 and a 99.7% positive feedback rating.
If you are interested to find out more about Peek A Boo, you can read more about it over at AtariProtos.com