Difficulty levels are a common means by which developers allow the player to make a choice about the amount of challenge they want to feel as they play through a game. Difficulty levels offer multiple choices to a player so that they can choose a level that is close to their level of skill, or merely choose a level that suits their playstyle best. The changes to the game that different difficulty levels make are different in every game, but some common characteristics to tweak are:
- The amount of enemies encountered
- The amount of damage enemies deal
- The amount of health/armour enemies have
- The amount of damage dealt by a player
- The amount of health/armour a player has
- The amount of weapon/health 'drops' in a game
- The use of tactics by the computer-controlled AI
- The accuracy of enemies (commonly seen in FPS games)
The most commonly-used difficulty settings are self-descriptive: Easy, Normal, and Hard. However, sometimes stylizations are used to better fit them within the theme of the game. For example, in Doom 3, the settings are Recruit, Marine, Veteran, and Nightmare, while in Diablo II, the settings are Normal, Nightmare, and Hell.
Many recent games increase or decrease the difficulty based on player performance. This allows for anyone to play the game with just the right amount of challenge without knowing the mechanics of difficulty variety. The Left 4 Dead games do this through the 'AI Director', though players are still allowed to choose a general difficulty level.