There are lots of game trainers for computer games but not as many for video game consoles. Most video game consoles are closed systems. To take advantage of hacks on a video game system without making physical changes to the console itself usually requires an extra piece of hardware for cartridge-based systems or a special CD for CD-based consoles.
Cartridge-based game consoles are traditionally difficult to hack. Game developers hard coded the video game onto a physical game cartridge. The video games are in read-only memory (ROM) format, which means it's very difficult to alter the code without special equipment and a keen understanding of programming.
That's where devices like Game Genie come into play. A company called Codemasters designed the Game Genie line of cartridge cheat devices. To use a Game Genie device, you simply plug a game cartridge into one end of the Game Genie and then plug the Game Genie into the game console. Codemasters made Game Genie cheat systems for several different game consoles.
The Game Genie intercepts the communications between the game cartridge and the console. The player has to enter a specific code upon startup to activate a specific cheat function. The Game Genie then alters the information coming from the game cartridge to produce the desired effect. In other words, the Game Genie acts like a hack. And best of all, since the Game Genie isn't altering the data on the cartridge itself you don't have to worry about ruining the game code.
Consoles that use compact discs instead of cartridges are a little different. For these systems, you normally use a CD that loads a few lines of code into the system's memory before removing the disc and replacing it with the actual game disc. A few systems also require the player to use a solid-state memory stick in conjunction with the cheat CD.
There's less of a need for hardware cheats today, since most game developers include cheat codes within the programming of the game itself. So far, the cheats we've talked about mainly focus on a single-player experience. Even someone who thinks cheating is bad would say you're really only cheating yourself if you use these techniques. But what about when you cheat against other human beings?