Game Development Reference
In-Depth Information
We've listed five types of mechanics, but there's another important distinction to
be made: Mechanics can be
discrete
or
continuous
. Modern games tend to simulate
physics (including timing and rhythm) with precise mechanics that create a smooth,
continuous flow of play. A game object might be positioned half a pixel more to the
left or right, and this can have a huge effect on the result of a jump. For maximum
accuracy, physical behaviors need to be computed with high-precision fractional
values; this is what we mean by
continuous mechanics
. In contrast, the rules of an
internal economy tend to be discrete and represented with integer (whole-number)
values. In an internal economy, game elements and actions often belong to a finite
set that does not allow any gradual transitions: In a game you usually cannot pick up
half a power-up. These are
discrete mechanics.
This difference between game physics
and game economies affects a game's level of dependence on its medium, the nature
of the player interaction, and even the designer's opportunities for innovation.
Understanding the Mechanics of Physics
Accurate physics computations, especially in real time, require a lot of high-speed
mathematical operations. This tends to mean that physics-based games must be
implemented on a computer. Creating a board game for
Super Mario Bros.,
in which
the gameplay requires moving and jumping from platform to platform, would be
difficult. In platform games, physical dexterity matters, just as it does in playing
real-life football; those skills would be lost in a board game.
Super Mario Bros
. is prob-
ably better mediated as a physical course testing players' real running and jumping
abilities. The point is, a rule that states that you can jump twice as high after pick-
ing up a certain item can be easily translated between different media, but actually
implementing that jump cannot. The continuous, physical mechanics of a game
need computing power more than the discrete rules that govern a game's economy.
Interestingly, when you look back at the early history of platform games and other
early arcade games, the physics calculations were more discrete than they are today.
The moves in
Donkey Kong
were much less continuous than they were in
Super Mario
Bros.
In
Boulder Dash
, gravity is simulated by moving boulders down at a constant
speed of one tile every frame. It might play slowly, but it is possible to create a board
game for
Boulder Dash
. In those days, the rules that created the game's physical
mechanics were not that different from other types of game rules. The early game
computers did not have any floating-point arithmetic instructions, so the game
physics had to be simple. But times have changed. Today the physics in a platform
game have grown so accurate and detailed that they have become impossible, or at
least inconvenient, to represent with a board game.
