Game Balancing - Fundamentals of Game Design - page 343

PERCEIVED DIFFICULTY AND IN-GAME EXPERIENCE
As they progress through a game, players learn to use the game's user interface
more efficiently, and they learn at an intuitive level how the core mechanics of the
game work. In-game experience at meeting any particular type of challenge may be
measured by the amount of time the player has already spent meeting similar chal-
lenges within your game. (Remember that you cannot know how much previous
experience the player has playing other games.) The more in-game experience a
player has, the easier he perceives a given type of challenge to be. Thus, when the
level designers build a challenge into a level, they must take into account the play-
er's amount of in-game experience with the same type of challenge. If the player
already has a lot of in-game experience with challenges of that type, the level
designers should consider raising the challenge's absolute difficulty to compensate.
The perceived difficulty of a challenge—the difficulty that the player actually senses,
and the type we are most concerned with—consists of the relative difficulty minus
the player's experience at meeting such challenges. Remembering that relative diffi-
culty is absolute difficulty minus power provided, we can put all these factors
together into a single equation such that
perceived difficulty = absolute difficulty - (power provided + in-game experience)
Note that there are no units of measurement for these variables, so if you want to
compute actual values for them, you will have to find a way to measure their quan-
tities based on the challenges that you plan to include in your game. The equation
serves more as a useful principle for you to understand than as a value you can
really compute.
Creating a Difficulty Progression
In a balanced game, the perceived difficulty of challenges presented to the player
either should not change or should rise, so the player feels that later challenges
present greater difficulty than those at the beginning. (If a game becomes easier to
play, players will definitely feel that the game is unbalanced.) In order to achieve
this, you have to take into account the player's increasing in-game experience and
build in appropriate increases in absolute difficulty. If you wish to, you can also
build in increases in the power provided by the game. Figure 11.3 shows this pro-
gression graphically. Notice the gap between the absolute and relative levels of
difficulty. This gap represents power provided by the game to meet challenges,
which widens steadily as the player gains power.
The gap between relative difficulty and perceived difficulty on the graph represents
the player's increasing in-game experience as she plays. At the beginning of the
game, the perceived difficulty exactly equals the relative difficulty because the
player has no in-game experience at all. As time goes on, her perception changes as
she gets more practice.