How did a plastic sleeve rewrite a NES game?
The Game Genie was an L-shaped plastic pass-through cartridge. A game cartridge slotted into the top of it, the whole stack went into the console, and a code screen loaded before the game did. The player typed in six or eight character codes and the game booted with more lives, more speed, or a level select the developers never shipped.
Nothing on the cartridge changed. The device sat on the data line between the cartridge and the processor and swapped single bytes as the chip asked for them. The Ninth Circuit put it plainly in 1992: "The Game Genie does not alter the data that is stored in the game cartridge. Its effects are temporary."
Codemasters, a British developer, built the hardware. Galoob, a toy company founded in 1957 and based in South San Francisco, took the United States rights and put the device in American toy aisles in 1990 at about $60, a figure Mental Floss cites for the launch.
Why did Nintendo take a cheat device to court in 1990?
Nintendo of America ran the NES as a closed system. It licensed every cartridge, capped what publishers could ship, and used a lockout chip to keep unapproved hardware out. A $60 sleeve that let an eleven year old skip the hard part was a direct challenge to that control, and Nintendo treated it as one.
The company argued that a Game Genie session produced a derivative work based on its copyrighted games, and that selling the device made Galoob a contributory infringer. Howard Lincoln, then Nintendo's senior vice president, said in 1990 that the company could not "stand by while the essence of our business" was put at risk by the product, in remarks Mental Floss later quoted.
Galoob and Codemasters had already gone to court first, asking a federal judge to declare that the device infringed nothing. Nintendo won a preliminary injunction anyway, and the Game Genie stayed off United States shelves for roughly a year while the case ran.
Was the Game Genie a derivative work?
That was the whole case. A copyright owner controls derivative versions of its work, and Nintendo said every altered game was one.
The Ninth Circuit disagreed on May 21, 1992, in Lewis Galoob Toys, Inc. v. Nintendo of America, Inc., 964 F.2d 965. A derivative work has to incorporate the original in some concrete or permanent form, and a Game Genie display incorporated nothing. It intercepted bytes in transit and left the cartridge untouched, so pulling the device out left the game exactly as Nintendo shipped it.
The panel added that the device "is useless by itself, it can only enhance, and cannot duplicate or recast, a Nintendo game's output." Even if an altered display had counted as a derivative work, the court held that a child changing a game at home for no commercial purpose was fair use, and that Nintendo had shown no market it was losing.
The 1992 opinion also carried a line hardware companies have leaned on ever since: "Technology often advances by improvement rather than replacement."
What happened to Nintendo's $15 million bond?
Preliminary injunctions are not free. To stop the sales, Nintendo had to post a bond that would cover Galoob's losses if the injunction turned out to be wrong. It was raised over the course of the fight to $15 million.
The injunction did turn out to be wrong. After Galoob won at trial, the district court ran a lost sales hearing and found the year off the shelves had cost the company at least $15,138,048 in profits, more than the bond covered. It awarded Galoob the entire $15 million, plus interest and the cost of restarting the line.
Nintendo appealed that too and lost again on February 17, 1994, in Nintendo of America, Inc. v. Lewis Galoob Toys, Inc., 16 F.3d 1032. The rule the panel applied, as the published summary of the 1994 decision states, is that "a party wrongfully enjoined is presumptively entitled to recover damages up to the bond amount."
Mental Floss puts the money Nintendo handed over in 1994 at $16.1 million. Few companies have paid eight figures for the privilege of winning a preliminary injunction.
Why did Galoob stop making them?
The product did not fail. Galoob sold about 2.5 million of the NES version through 1993 by Mental Floss's count, and millions more of the Game Boy and Super Nintendo versions after that. Versions for the Sega Genesis and the Game Gear followed.
What ended the line was the hardware generation, not the courtroom. Every Game Genie was built around a specific cartridge slot, and by the middle of the 1990s the money had moved to the PlayStation and the Sega Saturn, which read discs. There was no cartridge for the device to sit in front of. Action Replay and GameShark carried the cheat market onto disc consoles with memory card tricks and boot discs, and the Game Genie name stopped appearing on new hardware.
Galoob lasted a few more years on its own. Hasbro bought the company in 1998 for $220 million, and Galoob has been a Hasbro brand name since, turning up on die-cast collectibles rather than on anything that plugs into a console.
What does a Game Genie cost in 2026?
A loose NES Game Genie ran about $22 on PriceCharting in September 2026. A complete boxed copy sat near $59 and a sealed one near $92. Graded sealed examples are their own market, with one VGA 85 copy recorded at $813.
The Super Nintendo, Game Boy and Sega versions trade in the same band, and none of them are scarce. Galoob made millions, and most of those units are still in American basements.
Two things to check before buying. A manual alone runs roughly $8 to $20 on PriceCharting, so a listing that includes the code book is priced higher for a reason. And the device needs a clean card edge connection on both ends, which means a healthy cartridge slot in the console as well as in the Game Genie.
Where to find one today: a retro specialist sells tested accessories with a return policy, which is worth the premium over an untested auction lot at these prices. Stone Age Gamer stocks NES accessories.
Frequently Asked Questions
Who owns the Game Genie name now?
Hasbro. Hasbro bought Lewis Galoob Toys, the company that sold the Game Genie in the United States, in 1998 for $220 million, and Galoob has been a Hasbro brand name ever since. No Game Genie hardware has been built in that lineage since the 1990s, and later cheat products sold under a similar name were not the Galoob and Codemasters device.
Is it legal to use a Game Genie in the United States?
Yes. In Lewis Galoob Toys, Inc. v. Nintendo of America, Inc., 964 F.2d 965, the Ninth Circuit held on May 21, 1992 that changing a game's display at home with a Game Genie created no derivative work and was fair use. That 1992 ruling still stands and is cited whenever a console maker objects to third-party hardware.
How much is an NES Game Genie worth in 2026?
An NES Game Genie was worth about $22 loose on PriceCharting in September 2026, about $59 complete in its box, and about $92 sealed. Prices have stayed flat because Galoob sold roughly 2.5 million NES units through 1993, so supply is deep.