Difficulty level

Many games allow the player to adjust the difficulty level.

Common elements

 * Some games only allow the player to change the difficulty setting at the very beginning of a playthrough. Others allow the setting to be changed at the beginning of each level, and still others allow it to be changed at any time (for example, Minecraft).
 * The exact gameplay effects of the difficulty setting vary widely. In a shooter, higher difficulty levels might mean tougher or more numerous enemies. In a puzzle game, it might mean more complex puzzles. In some games, different difficulty settings might require the player to satisfy different objectives and restrictions to complete a given mission.

Functions

 * It allows players of varying skill level to enjoy the game.
 * It increases replay value: once a player has mastered the easier difficulty levels, they can still enjoy the challenge of beating the more difficult settings.

TODO: what about games which gradually ramp up the difficulty as part of the unfolding game experience (e.g., by sending increasingly numerous and tough waves of enemies at you)? is that part of this concept, or something separate?