Cheats
Cheats and the Game Genie
The most famous way to cheat on the NES is the Game Genie, a pass-through cartridge that sits between the console and the game. It intercepts the data the console reads from the cartridge and substitutes new values, letting you change game behavior without modifying the original ROM.
How it works
The Game Genie watches for specific memory addresses being read and replaces the returned byte with one of its own. A code therefore encodes both an address and a replacement value. Six-letter codes perform a straight substitution, while eight-letter codes also include a compare value so the swap only happens when the original data matches, which improves reliability across game banks.
Entering codes
- Insert the game into the Game Genie, then insert the Game Genie into the console.
- Power on to reach the code-entry screen.
- Enter up to three codes using the on-screen letter grid, then select start to boot the game.
Typical effects include infinite lives, invincibility, or starting on a later level. Because each code targets a particular game, codes are not interchangeable between titles.
Flash cart alternatives
Modern flash cartridges such as the EverDrive line often include a built-in cheat engine. You enter Game Genie style codes through the menu, removing the need for the physical adapter entirely.
Some codes can cause graphical glitches or crashes if they conflict with a game's logic; remove a code if it makes a game unstable.