Up-Up-Down-Down-Left-Right-Left-Right-B-A - Everyone remembers the Konami Code! And why shouldn't they; not only is its simplistic design catchy and memorable, but it also gave access to all of the awesome cheats and Easter Eggs from our favorite childhood games and continues to bear fruit today.
Although maybe the most memorable, first appearing in Gradius on the NES in 1985, it was not the first nor the last time gamers used ulterior mechanics to alter their gameplay experience. One of our favorites here at QD was the Game Genie.
Originally designed by Codemasters, this cheat cartridge was released in 1990 for the NES and wasted no time making the leap to the Super NES, Game Boy, Sega Genesis, and Sega Game Gear. The cartridge was simply put into the game system, same as any other cartridge, with the receiver attached to the device accepting games in the same format.
Finding itself between the console and game, the device worked by prompting the player to ender a code that referenced addresses in the ROM of the game cartridge, each code containing an integer value that was read by the system in place of the data intended to be delivered by the cartridge. The console being none-the-wiser accepted those inputs too openly. The cheat device came with a booklet of known codes, but wasn't limited as the player could enter any combination they liked, sometimes leading to no change at all, or even corrupting saved game data on the game cartridge itself.
This technique has been used many times since, but the Game Genie holds our QD title for most original cartridge cheat out there.