Machinations - Game Mechanics: Advanced Game Design - page 95

Gates might have only one output. Gates with one output act the same way as gates
with multiple outputs. The gates on the middle row of Figure 5.16 will (from left to
right) randomly let 30% of all the resources pass, immediately pass the resource to the
output regardless of the output's flow rate, and let only the first two resources pass.

All output state connections from a gate are triggers; gates do not accumulate
resources, and therefore label modifiers, node modifiers, and activators originating
from a gate serve no purpose. These triggers can also be conditional or probabilistic.
In this way, gates can be used to control the flow of resources ( Figure 5.17 ).

FIGURe 5.17
an automatic, ran-
dom gate controlling
the flow of resources
between two passive
pools. in this case,
there is a 30% chance
that three resources
will flow from a to B
every time step.

Sources
Sources are nodes that create resources. They are represented as a triangle pointing
upward ( Figure 5.18 ). Any node in a Machinations diagram can be automatic (the
default), interactive, or passive, or it can activate once before a diagram starts. An
example of an automatic source is the steady regeneration of the protective shields
of the player's star fighter in Star Wars: X-Wing Alliance . The action to build armies
in Risk would be modeled as an interactive source of armies, and passing Go in
Monopoly would be a passive source of money that is triggered by a game event. The
rate at which a source produces resources is a fundamental property of a source and
is indicated by the flow rates of its outputs.

FIGURe 5.18
Unlimited and limited
sources

In many ways, a source acts just as a pool without inputs that starts with a suf-
ficiently large (or even infinite) supply of resources. However, to model limited
sources (see the section “Four Economic Functions” in Chapter 4), it is better to use
a pool with a specified number of resources in it.

Drains
Drains are nodes that consume resources; a resource that goes into a drain disap-
pears permanently. The Machinations framework includes a special drain node
represented as a triangle pointing downward ( Figure 5.19 ). The rate of a drain is
determined by the flow rate of its input resource connection. Some drains consume