A runtime game Game Enhancer which can modify ROM addresses and was developed by Codemasters. It is the first cheat device to use encryption. In the United States it was sold by Galoob.
History
The first Game Genie to be released was for the NES. It was met with strong opposition by Nintendo and it was prevented from being distributed in the US as a lawsuit was underway. It was sold openly in Canada and when Nintendo lost the lawsuit it was finally released in the US. It was then released for SNES, Genesis, Gameboy, and Game Gear. The portable versions would have a small opening to inseart codebooks which contain the cheat codes.
A version for the Sega-CD was in the works but was ultimately cancelled. It was to fit inbetween the Genesis and Mega CD on the model which requires the systems to sit side-by-side.