Interface - Designing Games - page 223

Metaphors can also imitate higher-level concepts in the modern world.
We can reference systems in economics, politics, biology, or psychology, as
long as players understand them. There are games with systems that imi-
tate supply and demand ( Privateer ), the division of electoral politics into
various issues ( The Political Machine ), and the way people form and break
relationships ( The Sims ). In no case is the metaphor a perfect simulation
of the real system. But as with folders, it's close enough that the meaning
gets across.
But the most common form of system metaphor is the most abstract:
the use of mathematical systems like numbers, time, and space. For exam-
ple, in chess, there are 64 squares with 2,016 relationships among them.
These 2,016 relationships could have been expressed in any number of
ways. We might have written a long list of every relationship: a1 is left of b1;
a1 is two squares left of c1, and so on. Or we might have represented each
square with a Ping-Pong ball, and used 2,016 colored strings to mark the
relationships. Or we could have chosen any other representation. In each
case, the fundamental system of chess is intact—but the game is incom-
prehensible. It's only when we put the 64 squares on a 2D plane that the
game becomes playable. By imitating real space itself, chess leverages the
human brain's natural ability to think about complex spatial relationships.
Systemic metaphor like this is nearly universal because of its incredible
elegance.
metaPHoR voCaBulaRy
Cars in video games usually move forward on wheels. Sometimes they
need fuel. It is quite rare, however, for them to need oil changes, have
registration numbers, or get parking tickets. Similarly, game people often
don't go to the toilet, game dogs never get fleas, and game food rarely
spoils.
Only a small subset of the functionality of the real object is actually
implemented in game mechanics.
The implicit contract between player and designer says that the de-
signer will use metaphor to help the player learn, and the player won't
complain when the mechanic doesn't express every property of whatever
it imitates. But this creates a problem for the player. Now he has to figure
out which aspects of the game are real game mechanics, and which are
just fictional dressing. It's up to designers to make this as easy as possible.