Is difficulty compelling in gaming?
Levels of difficulty can be, and often are, considered to be a mechanism by which a player can gauge their ability relative to the challenge the developer sets. In video games that offer difficulty levels, balance and pacing are generally designed on the basis that most players will initially pick the default setting, 'Normal'.
Forgive the excessive generalising that I'm about to do. Those who pick 'Easy' are either non-gamers or playing the game solely to experience mechanics that aren't changed by the difficulty level without being impaired by the mechanics that are. Those who pick 'Hard' are those who have either played through the game on Normal and wanted to have another go with a bit of an extra challenge, or are looking to overcome the worst that the developers can throw at them.
Some games cater to both crowds very effectively. Games like Devil May Cry, Viewtiful Joe and Bayonetta offer easy modes that are simplistic to the point of literally asking the player to press one button, all the way to difficulty modes far beyond 'Hard' and into 'Unreasonable' and 'Bullshit You're Such An Asshole, Game'. They even use difficulty as the carrot with which to extend the lifespan of a game; in Devil May Cry, Hard mode is locked until you have beaten the game on Normal. You then unlock more difficulty levels by beating the game on Hard. To me, that's quite a compelling way of rewarding finesse and skill without extending the development time of a game to astronomical levels. There are tons of games that I love to death, but will never replay again, because there is little incentive to come back and blast through a game with already-learned skill. Clearly, there are exceptions, games which earn replays through their sheer class and brilliance; even so, Master Quest is one of the best things to happen to Ocarina of Time.
Something I have discovered, due to being fortunate enough to know gamers who fall into all spectrums of gaming, from the atmosphere-chasing easy-moders to the grizzled steel-chewing veterans, is that your choice of difficulty has the potential to completely skew your perceptions and experiences of a game compared to someone who picks a lower or higher difficulty. Or, alternatively, it might not. As an example of the former, I have been playing Shadow Complex on Hardcore, the difficulty above Normal. When I analysed the game with my brother, who had been playing on Normal, we discovered that I had been playing a much more combat-oriented experience than he did; I was playing Contra with some platforming sections, and he had been playing Symphony of the Night with some guns. The reality of how Shadow Complex is structured is closer to my brother's experience, but the shift up in difficulty made a tacked-on activity in the game become meaningful and challenging.
Modern videogames have increasingly adopted the health system popularised by Halo, in which you have a small health pool that regenerates rapidly after a few seconds of no damage. The reason for the implementation of this health mechanic is that it more accurately simulates the danger of bullets and taking damage - you cannot sustain as much damage in a battle, which adds elements of vulnerability and danger to your decisionmaking process.
It also turns difficulty into a gauge of the player's patience; specifically, how much of his time he is prepared to sit and regenerate health. This is more forgiving than a finite health system, because it allows you room to recover from an error at the expense of time where in a finite system you would be permanently at a deficit. It also encourages a dull style of play, and consequently erodes the relevance of a difficulty select screen - in Halo, choosing Heroic or Legendary is more of a test of your patience than your accuracy, reflexes and finesse. I am replaying Mass Effect 2 on Insanity, the highest difficulty, and I am definitely finding it very tough going. Unfortunately, that's more because I am getting quite tired of staring at Shepard hiding behind a box than the game itself being challenging in any meaningful way. Mass Effect 2 is a wonderful game that is rendered dull and boring by turning up the difficulty, where really one would expect the reverse.
It is unfortunate that developers sometimes limit the possibilities with which they can challenge their audience by implementing mechanics such as this. Having more dudes that shoot you harder is a viable strategy for scaling up difficulty, but not when it becomes the only real method of increasing difficulty.
There are many wonderful examples of inventive difficulty scaling. The one that is permanently burned into my brain is the fourth level in Perfect Dark, the Carrington Institute: on the first two difficulty levels you are tasked with shooting two interrogators in order to save a friendly negotiator. Upon revisiting this level on the hardest difficulty, you double-take as the cinematic ends and you find yourself in the negotiator's costume, without a sniper to save you. No pressure.
While that is undoubtedly an extreme case, Perfect Dark is a good example of an older format of FPSes, in which higher difficulties bring not only harder and more plentiful enemies, but also extra objectives. On the lowest difficulty, you will likely find yourself simply having to make your way to the exit, but as you select higher difficulties the developers incrementally add more objectives which will require the player to approach the same level with a wildly different strategy and encourage the player to explore its environment again.
Bayonetta takes another approach, by actively handicapping you and removing your bullet-time (cough, Witch Time) ability. This is another good use of the difficulty option, but these are simply examples among a litany of inventive ways developers have made their games optionally harder and encouraged replayability through the format. The common thread here is that adding and removing content incrementally can have a comprehensive impact on the difficulty of a game, and is far more consistent in its success than the simple modification of numbers - while Shadow Complex becomes an entirely different beast with the strengthening of its enemies, Halo and its disciples suffer for it. Having written this and looked back, I'm aware that I rely heavily on anecdotal evidence from FPSes. Go ahead and post examples of the types of difficulty that you appreciate in whatever it is you've been playing since... well, since you first picked up a pad. I'm interested in hearing what people generally find interesting when it comes to challenge in video games.