Technical reasons:

Quality assurance teams depend upon cheat codes to be able to test things in a video game.

Marketing folks depend on cheat codes to demo certain sections of a game at trade shows without having to play through the game normally.

Sometimes an unfixed bug in a video game gets you stuck in a spot that you can't get out of unless you use a cheat code. An example would be if you fall into a crack in the world geometry that the QA team never caught, and you get stuck. A clip-through-walls cheat would get you out of there. And then there's the places where the game genuinely can't be finished without cheating because of an unfixed bug: Look at the Skyrim wiki sometime... Every single major quest in that game has a bug note saying, "If you accidentally do X before completing Y, then the Z quest will never finish. To get around this bug, type cheat code Q."

There might be a hidden easter egg of some kind that you want to see that isn't accessible without a cheat code (i.e., Romero's head in Doom).

Using things like clip-through-walls cheats is a great way for budding game designers to explore and investigate how the levels were created, to learn about game design.

Using cheats which change game mechanics is a great way for game designers to explore the various ramifications of different types of game mechanics and difficulty curves.



For a puzzle game like Portal, I completely agree. The point of those challenges is to have fun trying to do the difficult parts. Cheating would definitely defeat the purpose in that case.

In that case and in many other cases, single-player cheating turns out to be self-defeating. By cheating your way past the parts of the game that are difficult, you quickly discover that the difficulty was actually the part that you enjoyed, and the part that actually held your interest and concentration.

But there are other situations when using cheat codes can be useful in a single player situation, and increase your enjoyment of the game rather than spoil it.

My favorite example of this is encumberance in RPGs. It's a game mechanic that the designers deliberately insert into the game to make the player backtrack to town to sell goods after adventuring in a dungeon. It's a boring mechanic that I find exceedingly tedious, and which makes me shelve certain RPGs fairly quickly. In most RPGs, I would never have the patience to finish the game if I didn't have access to an encumberance cheat. This isn't a case of making a difficult thing easier... there's nothing difficult about going back to town and selling your loot, it's just tedious. Having to stop your adventure mid-dungeon because your inventory is full is simply annoying.

Basically, that's making a choice to change a game mechanic that you dislike. If you can enjoy the rest of the game while fixing that one game mechanic, there's no problem with using a cheat code. And if removing that game mechanic unbalances the whole game experience, making the game un-fun, well, then that's the self-defeating thing mentioned above: you simply come to the realization that the difficulty was part of the game, and you either stop playing the game (the annoying game mechanic was the deal-breaker for you in that case, oh well), or you go back to playing the game without the cheat code.

Sometimes game designers will eventually acknowledge that an annoying game mechanic was bad to begin with, and it's cheaters who convince them of this. Witness Doom 3, which originally had a game mechanic where you could EITHER have a flashlight OR a gun, but not both. The game experience was designed around the "boo" moments in dark corridors, and the Cameron-Aliens-style gunfights in the dark where the only light was muzzle flashes. They released Doom 3 like that, and critics and players universally lambasted it for not allowing flashlights and guns at the same time. The first user cheat for the game was called the Duct Tape Mod, which allowed you to "duct tape" a flashlight to your gun. Players actually enjoyed the game more with the mod than without it. And now, they're re-releasing it for the Xbox this year, and guess what? You can have flashlight and guns at the same time in the Xbox version. (And they're touting that as a big feature. Ha!)

But what about times when the game mechanics aren't annoying, rather, they're simply too hard for some players? In action games, some players lack the skill to defeat the toughest bosses. I think they have every right to cheat themselves a bit of extra health or ammo so that they can bring that last boss down and see the ending of the game. I know that if I'd paid 60 bucks for a game and then hit a brick wall in the difficulty curve, I'd feel it was my right to get as much enjoyment out of the game as I'd paid for. Here's an example: I bought Lost Planet for the Xbox a few years ago. Instead of having a standard save-game system, it has a checkpoint system. Well, one of the checkpoints mid-game was poorly placed, and it saved my player's progression at a point where the player had no way to progress forward without dying at the hands of a very powerful monster, but also no way to go back to get health and ammo. If I'd had access to a health cheat, I would have used it there, and continued the game on to the end. Instead, I have shelved that game, never finished it, and never played its sequels.