There are several ways to cheat in games. One is to ignore the spirit of the game. It's fairly obvious what the programmers of games intended it to be played like. However, it's very difficult to anticipate every strategy likely to be employed to complete a level so sometimes there are loopholes. For example, in Destruction Derby 2 you're expected to cane your car round the track, causing crashes for points, which is great fun. Unfortunately, it's much easier to rack up a high score by parking your car on a narrow bit of track and waiting for cars to crash into you. The programmers hadn't thought of this and didn't stop the race until you had finished or died; the drone cars just kept going round, lap after lap, until you destroyed them. Hey presto! You're on the high score table.

The second type of cheating is to exploit system bugs. This means that if you notice a loop in the AI, or an unintended shortcut, or any number of other glitches you can use this to your advantage and then pretend you'd played the game properly. This isn't always that common but can happen. Mortal Kombat was a good example. It was actually possible to win all the time by leg sweeping continuously, which caused an unblockable loop.

The third way is to get someone else to play a game and write a walkthrough guide, then follow exactly in their footsteps.

The final way to cheat is to hack into the code itself. There are many ways to do this. Even as long ago as the first home computers, the POKE code to be hacked into the program loader for infinite lives, etc, was hot property. Now there's a positive industry in this, with add-ons like Datel's Action Replay long-time top sellers. So prevalent has this become that, long ago, programmers began to include cheats in the game code itself, rather than to futilely try to stop hacking. Requests for cheat codes often happen before the game is even released, and magazines capitalise on the lure of having a good cheat page to ensure sales. Now all you need is access to the right combination of button-presses and you can pretend you're good to your heart's content.