The Game Genie was a device made by Galoob that allowed players to hack their games, much like the Gameshark and Action Replay. Models were made for the NES, SNES and original Game Boy. They were also made for the SEGA Genesis and Game Gear.
The Game Genie could not save codes, so you had to enter the codes each and every time. All three came packed with a booklet of codes. A magazine subscription would allow more access to codes before the internet came to be. The SNES and Game Boy models also had a button or switch to turn the codes off and on while playing in case of situations where the codes may impair the game.
At CES 2012, a company named Hyperkin they said they were going to bring back the Game Genie for the 3DS, DSi, DSi XL, DS Lite, DS, and Wii, along with a new device called Save Guru.