Interesting thread. I like the term "artificial difficulty". Even though all games are completely artificial by nature, I think it's pretty clear what you mean by it.
I take issue with a couple of things though.
PedroSteckecilo said:
Resident Evil 4: Shooting Ability and Decisions are important (though ammo scarcity fits into Artificial Difficulty territory, as do escort missions).
Ammo scarcity is another word for "resource management". Nothing artificial there. You have a limited amount of resources (bullets) and you have to make the best possible use of them. Strike a balance between careful aiming and quick shooting. Don't use shotguns on a lone enemy unless the situation is desperate. Manage your grenades judiciously.
Escorting Ashley isn't artificial either. She's a material target for the enemy and you need to balance the need to protect yourself with the need to protect her. Sometimes you can afford to let them carry her off for a little while (as you thin their numbers around yourself) but you can't let it go too long or it's all over.
PedroSteckecilo said:
Grand Theft Auto (1, 2, 3, Vice City and San Andreas): The controls suck, the cars are too weak and the autolock frequently targets the wrong foe.
Serves you right for playing it on a console instead of PC with mouse and keyboard.
PedroSteckecilo said:
You often end up dying four or five times on a mission because of something stupid, like a random car drives into the intersection during a crucial car chase and destroys you,
So. Annoying. The fact that you can't anticipate or deal with those problems except by repeating the missions until you get lucky is what really burns. Though somehow the phrase "artifical difficulty" doesn't seem to apply here. It seems like random screwage, rather than something the designers deliberately put in. I wonder, is it useful to make the distinction?
Anyway. My least favourite is AI cheating in RTS and TBS games. I remember playing the original Civilization on Emperor level, and I couldn't understand how my neighbours were managing to grow their cities so damned fast. Eventually I sent in a diplomat to spy on their production and realized that the food and production icons were oddly staggered in their respective boxes. The AI only needed 1/6th the food to grow its population and 1/6th the production to construct its buildings and military units. I turned the machine off and have never enjoyed the game quite as much since. THAT's artificial difficulty for you.
AIs who always antagonize the player and rarely antagonize each other are also irritating. Let 'em win or lose on their own merits, the lazy bastards.