Emergence and progression - Game Mechanics: Advanced Game Design - page 37

Structural Differences
To understand the difference between progression and emergence a little better,
let's look at the structure of the mechanics that create the two different types of
gameplay. Games of emergence are characterized by only a few rules. In a game of
emergence, complexity is created by many connections and interactions between the
rules, rather than large numbers of rules. What is interesting with this type of game
is that the complexity of the gameplay leaps up after reaching a certain point in
the complexity of the rules. We already saw a similar jump in gameplay complexity
in the discussion of tic-tac-toe and Connect Four . Figure 2.5 illustrates that turning
point, which we refer to as the complexity barrier . Beyond a certain point, interac-
tions among the rules create an effect that is sometimes called the explosion of the
probability space . In general, mechanisms that contribute to emergence in games add
many different possible states to the game. Large probability spaces make games
more replayable; as a player, you can be confident no two games will be exactly
alike. This adds to a game's appeal, especially if the outcome of each play-through is
as unpredictable as the first.
FIGURe 2.5
The complexity barrier
is the region between
the two dotted lines.
Games of progression usually possess many rules but far fewer interactions among
the rules. The mechanics that control player progress through a level hardly inter-
act with similar mechanisms in the game. Many of the mechanisms serve a single
purpose: to keep players from reaching a certain place until they have accomplished
some other task first. In effect, these mechanisms can be in one of two simple states:
A door can be open or closed, a key can be found or not. Mechanisms that contrib-
ute to progression rarely add many different states to the game, but they are easily
controlled by the game designer. The advantage of progression is that the designer
can dictate the order in which players will face challenges and learn skills and can