FUNDAMENTALS OF GAME DESIGN, SECOND EDITION
Establishing Difficulty Modes
In creating a single-player game, you should allow the player to choose how difficult the game will be, typically with three options labeled easy, normal, and hard, or similar terms. When players make this choice, they're playing in a difficulty mode, such as easy mode or normal mode. (Don't confuse these with gameplay modes.)
Multiplayer games don't always offer different difficulty modes because in many multiplayer games the player's skill determines how hard it is for others to beat her or for her to beat them. But in multiplayer games in which the environment itself sets challenges for the players, such as a road race, the players may want to choose the difficulty of the environment's challenges—to select easy, normal, or hard courses to race on, for example.
When you create a game that offers the player a choice of multiple difficulty modes, in effect you promise that the perceived difficulty of the game will never go above a certain point throughout a game level.
How you adjust the difficulty of challenges for different modes depends on the challenges and on the genre of your game. In action and action-adventure games,
for example, designers normally give the enemies more health, allow them to do more damage, and make them more numerous. Designers also sometimes adjust the AI of enemies and artificial opponents, making them smarter or more aware of threats. Chapter 9 discusses how to adjust the absolute difficulty of different kinds of challenges.
DESIGN RULE Easy Mode Means Easy!_____________________
Some games, usually those built by game developers who are also hardcore gamers, offer the player an easy mode that isn't really easy at all. If you're going to call it “Easy Mode,” it really should be easy for even an inexperienced player. Players choose Easy Mode for a reason; if they want a more challenging experience, they can choose a harder mode. Don't assume that you know what “easy” is. Try your game out on some inexperienced players and see how they react, then tune your Easy Mode for them.
In some cases, you may not be able to adjust the difficulty level of a challenge at all. With something like a static obstacle, such as a cliff the avatar must climb, the challenge is built into the shape of the cliff, and adjusting its difficulty would mean redesigning the landscape on the fly. Instead, give the player an alternative route that avoids the cliff climb in the easiest mode, but lock off the easy route in the harder modes.
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DYNAMIC DIFFICULTY ADJUSTMENT
Over the years, game designers have made a number of efforts to create games that detect the player's level of skill and adapt themselves to change the player's experience accordingly. Several approaches have been tried:
• The first-person shooter game Max Payne automatically adjusts the strength of enemies and the amount of aiming assistance provided to the player based on his performance. The changes work to keep the player's experience at an appropriate level of difficulty, but they are transparent to the user.
• Half-Life 2 checks the state of the avatar's health and ammunition when he breaks open a crate in the game world, and adjusts the contents of the crate accordingly. If he is healthy and well supplied, he might find little or nothing, but if he is short of one of these resources, he might find medical kits or spare ammunition.
• The racing game Burnout 2: Point of Impact automatically changes the performance of computer-controlled drivers to keep them near the player's car regardless of how well or poorly she does. No matter what the skill level of the player, this approach ensures a close race.
• Crash Bandicoot, an action game, offers the player extra shields against attack if he fails to get through a certain section too many times in a row. Players find this mechanism rather obvious. Furthermore, rather than being a global system like Max Payne’s, it had to be implemented separately for each region of the game where it offered extra shields.
• Madden NFL 09 gives the player a series of explicit tests in its “Virtual Training Center,” then adjusts the difficulty of the gameplay in the real game based on his performance in the tests.
• God of War, another action game, detects when the player is dying frequently and offers him the chance to play again in a lower difficulty mode. In this case, the game doesn't adapt its difficulty; it simply offers the player the chance to choose an easier mode. Some players complain that they find this patronizing; presumably others find it a relief.
DDA systems such as those used in Max Payne and Burnout 2 are the subject of considerable debate within the game industry and for the moment remain experiments rather than standard industry techniques. Some designers believe that no automated system can accurately predict how hard a player wants his experience to be, so they should not even be tried. In fact, as with everything else in game development, there are tradeoffs. Good DDA systems are time-consuming to build and tune, but they can significantly enhance the player's experience if done well.
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DYNAMIC DIFFICULTY ADJUSTMENT
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You should not try to implement a DDA system in a beginner-level project. Learn to build and tune games in the conventional way first. However, if you are a more advanced designer or you have been assigned the task of developing one, consider the following:
Any DDA system requires two mechanics: a performance-evaluation system to measure how well the player is doing, and an adjustment mechanism to change the difficulty of the challenges he faces. How you do this will naturally depend a great deal on the kinds of challenges you're offering.
• Don't use DDA as a substitute for ordinary difficulty modes that the player can set.
Players like to have the freedom to limit the maximum difficulty level of the game.
• Make it optional, a feature the player can accept or reject. DDA systems are often used in conjunction with player-settable difficulty modes.
• Use it to make the game harder but not easier. It is generally simpler to make a game more difficult than to make it easier. To make a game easier under computer control, the software has to determine the reason for the player's failure, which isn't always clear or measurable. Making a game harder doesn't depend as heavily on the computer's understanding of the reasons for the player's success.
• Never arbitrarily take something away from the player, especially something that he feels he's earned. It's OK to give the enemies more weapons; it's not OK to take weapons away from the player.
• Keep it subtle—this is the most important advice of all. The best DDA systems are the ones the players never even notice. Max Payne is a good example; God of War is a bad one.
As long as your adaptive-difficulty system remains an optional means of making the game extra challenging for the hardcore player, it will be less prone to the problems observed with such systems because the player cannot manipulate it to her advantage, and she can switch it off if it becomes a problem.
DDA is an advanced design topic, and there isn't room to cover all its nuances here. You can read more about the subject in the Gamasutra article “Difficulty Modes and Dynamic Difficulty Adjustment” (Adams, 2008).
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