How to Solve It: Broadly, there are two aspects to challenge in games, one that may be related to interface, and one that may be related to parametric design. The former, involving the difficulty of mastering the interface of the game (that is, the mechanisms that allow the player and game to communicate, which include the game controls, HUD data, vision modes, audio cues, and so on) can be made easier via player aids, as discussed previously.

Parametric difficulty is based around the qualities of the contents of the world. Games are made up of numbers, such as the health points of an enemy, that enemy's distance from the player's gun, and the damage levels inflicted by a direct hit from that gun. These numbers -- parametric values -- can create difficulty. If the enemy has a million hit points and the gun does one hit point damage per hit, the enemy will take one million hits to kill. If the enemy fights back at all, this can also increase the difficulty in fighting him.

Both types of difficulty must be addressable by players. This is true of all players -- they have paid for the game, and so should expect to be able to play it. Games of Hard Fun, however, thrive on being just slightly harder than players can deal with on their first play; if players can decrease the difficulty, this can be seen as a "cop-out" or "cheating".

This doesn't cause problems with a classic difficulty selection system (which involves a player choice before the game begins, usually between easy, normal, and hard modes -- although even here players are at the mercy of the developer's interpretation of these terms with regard to the actual difficulty of its game). But there is a general assumption within the games industry, possibly still a holdover from challenge-oriented twitch arcade games, that because interface difficulty seems to decrease as the game progresses (because the player gets better at using the game), parametric difficulty must increase. Not only that, but it is often assumed that the overall difficulty at the end of a game should be significantly higher than at the start.

Although part of this fits the idea of Flow you learned about in Step 1, these assumptions can become highly dubious in practice: no one can know in advance how much better an individual player will become from continued play, and without access to this kind of information, it is impossible to know if it is appropriate to increase difficulty.

To maintain full accessibility, game difficulty should be manageable by the players on the fly, at any point in the game. This suggestion may immediately incense any player who is primarily concerned with Hard Fun. If a reasonable strategy to bypass a bottleneck in parametric difficulty is to choose an option from a menu, surely the point of the game is completely diminished! But since such players consider these kinds of changes to be "cheating," doesn't this problem become self-limiting? And of course, players who play for any of the many other reasons players play games need not fear this at all.

Videogames that have allowed for flexible difficulty settings throughout the game include Magic and Mayhem, Disgaea: Hour of Darkness, and Oblivion. Since Oblivion has sold more than 3 million units, as well as scooping up several Game of the Year awards, it can safely be assumed that allowing players to change the difficulty setting at will isn't a significant barrier to commercial success anymore.

The fact of the matter is that people who work in videogame development routinely misjudge just how difficult their game might be for someone with considerably less game literacy, let alone someone with accessibility issues. There is no need to shy away from making supremely easy difficulty settings, because players seeking a challenge will not choose a setting called "insanely easy" or anything of the kind (such players often balk at playing on Normal!). Making the easiest difficulty setting in a game as simple and easy as it could possibly be will benefit a vast number of players, and not just those with disabilities.