Game Development Reference
In-Depth Information
Core Mechanics
Football is brutal only from a distance. In the middle of it there's a calm, a tranquility…
When the systems interlock, there's a satisfaction to the game that can't be duplicated.
There's a harmony.
—D
ON
D
E
L
ILLO
,
E
ND
Z
ONE
Sports games present a number of design issues that designers of other kinds of
games rarely encounter. This section covers issues raised by the physics, AI, athlete
skill ratings, and other aspects peculiar to sports games.
Physics for Sports Games
During play, your game will be running a physics engine that determines the
behavior of moving bodies in the match. The physical behavior of an inanimate
object such as a baseball is comparatively easy to implement. The physical behavior
of humans, however, is much more complicated. Early sports games tended to treat
a running athlete rather like a rocket: She had a velocity vector that gave the speed
and direction of her movement and an acceleration vector that gave the force and
direction with which she pushed. Modern sports games have much richer simula-
tions with a great many variables, taking into account such things as the friction
coefficient of the playing surface—for example, rain and snow make fields slippery
and reduce traction.
Designing the physics simulation for a sports game is a highly technical problem
and is beyond the scope of this topic. However, beware: Because a sports game is a
simulation of the real world, it is a common error to think that the physics in a
sports game should be as realistic as possible. It shouldn't be, for two reasons:
First, the player is not actually running around on the playing field herself; she
is watching a screen and controlling an athlete through a handheld controller. She
has neither the immediate experience of being on the field nor the precise control
over her movements that a real athlete does.
Second, the player is not a professional athlete. There is a good reason why only
a small number of people can hit a baseball pitched at 95 miles per hour. The
length of time that the ball is within reach of the bat is about 0.04 seconds. It's
simply not realistic to expect that an ordinary person looking at a video screen
without the benefit of depth perception could react quickly enough to “hit” a ball
thrown at this speed.
For both of these reasons, you need to adjust the physics to make the game play-
able. In a baseball game, slow the pitch to give the batter a reasonable chance of
hitting the ball, and artificially adjust the position of the bat so that it intersects
the path of the ball. Whether the physics perfectly copies that of the real world
doesn't matter as much as whether the game seems to be producing a reasonable
