[Game design veteran Sigman presents a detailed look at how game mechanics can be represented visually -- and what we can learn about how to make great video games thanks to such alluring graphs.]

Whether discussing game features amongst the design team or communicating them to programmers, lack of proper terminology can obfuscate messages. (Just like how using the word "obfuscate" can obfuscate messages.)

Coders have technical backgrounds and most went through rigorous college-level math classes. As a result, if a designer is trying to explain a desired mechanic but using the wrong terms, the message content can be lost.

The foundations of math provide a convenient basis for understanding most game mechanics, so it generally makes sense to describe game mechanics in established mathematical nomenclature.

The first part of this article is a short primer on visual representation of game mechanics and some proper terms to describe those representations. The second half discusses a few selected game mechanics in more detail for illustrative purposes.

Visual Value in a Graph

A picture's worth a thousand words.

No, seriously. I was trying to think of a wittier, more concise way to explain the value of talking about game mechanics visually, but societal wisdom beat me there.

The hitch about using visuals is that you still need a way to describe them. So you kinda still need those thousand words after all. So let's dive in with some foundation items, and then we'll get to the fun stuff.

Term: Function

Mathematically, a game mechanic is usually just a function. A function is a mathematical "black box". Given a certain input, the black box (game mechanic) creates an output.

Game Mechanics are Functions (Black Boxes)

Graphically, a function is represented by a line or curve in an X-Y plot:

A Function

Term: Domain

Function Domain

A game mechanic's domain is the range of values over which the mechanic is active. Graphically, this is represented by the X-axis ("abscissa").

Take an example game mechanic: "shooting accuracy as a function of RIFLE skill." The domain is the RIFLE skill range -- say 1-10 or 1-100 or whatever your game system is.

Another example is the mechanic "acceleration as a function of transmission gear." In this case, the domain is the range of gears in the vehicle -- say 1 through 5.

Term: Slope

Slope

Slope refers to the angle of the line or curve of a graphed mechanic. Technically, slope is described as "rise over run", which is just the change in Y value for a given change in X value. Negative slope means downward trending; positive slope is upward trending.

Conceptually, a high slope means a fast-changing mechanic, whereas a low slope is a slowly-changing mechanic.

High and Low Slope

Whether the mechanic is linear or non-linear (see later), you can always still define a local slope. In the case of a linear mechanic, the slope is constant; for non-linear mechanics, the slope changes all over the place.