Game Genie is a line of video game cheat cartridges originally designed by Codemasters, sold by Camerica and Galoob.  The first device in the series was released in 1990 for the NES (sold by Camerica and the item that is in this listing), with subsequent devices released for the Super NES, Game Boy, Genesis, and Game Gear.  All Game Genie devices temporarily modify game data, allowing the player todo things unintended by developers, such as manipulating various aspects of the game and accessing unused assets and functions.