Gamma-Attack (1983)

Gamma-Attack was programmed by Robert Esken Jr. and released by Gammation in 1983. Guinness World Records calls it widely believed to be the rarest cartridge in the world, with a single copy known to exist, and its owner listed that copy on eBay in 2008. Here is the tension that makes it interesting: the game's code has circulated for years and reproductions are easy to find, including a signed run of 100 from its programmer, so almost everyone who has played Gamma-Attack has played a copy. The original remains a story told about one object.