Here’s a theory I came up with years ago.  It came from reading lots of tabletop RPG books, but as we’ll see, it applies to other types of games as well…

Most games appear to consist of three basic components:

• Mechanics are the rules, the guidelines that tell you what happens, when.
• Statistics are data to be used with the rules.  They often tell you how to use certain things (ideas) with the rules.
• Setting is information that has no game effect; it’s there to explain the “world” to the players, set the mood and the atmosphere, and so on.

Some examples will make this clear.  Let’s think about, oh, say a space opera sci-fi RPG.

• The mechanics will tell you what character attributes mean, how to use dice to resolve things, how space combat differs from hand-held laser combat, and so on.
• The statistics will tell you how to use different spaceships, weapons, character races, etc. in the game.
• The setting will tell you what these various alien races are doing wandering around in the universe shooting at each other.

These divisions apply to computer games as well, of course.  Mechanics would be the game “engine”, the rules that specify how game elements interact; statistics are data and assets used with the game, specifying the game elements…and the setting would be anything displayed to the player that doesn’t have a direct game effect, as well as manuals and such things.

Thoughts About Mechanics

Mechanics generally comprise only a small portion of tabletop RPG books.  Of course, they’re perhaps the most important; merely changing how dice are rolled can have a very different effect on how a game plays.  Intuitively, it seems as though mechanics are “the most important”.

Historically, computer game mechanics have been the most difficult part of the game to create; that’s where you have to have the computer actually do stuff, after all, like input and output.  Recent tools are making this easier, though.  With modding, you can use someone else’s mechanics and your own stats and setting.

Thoughts About Stats

If mechanics comprise only a small part of a game system, then statistics probably make up the largest part.  They provide the environment the players wander around in, and that leads to interesting decisions.  For example, providing a list of weapons means players get to choose which one to equip.

RPG supplements are nearly all stat.  This is where a lot of the creative hard work is done.  (Mechanics seem more like “flashes of genius”, but I’m sure there’s a lot of testing and iteration involved.)

Some games are basically defined by their stats.  Magic: the Gathering, for example, releases a new set of cards every few months.  These cards almost all work with existing rules, with a few simple additions and revisions each time.

With more game engines and game tools becoming public, more and more people are getting into creating stats.

Thoughts About Setting

It might seem that setting is the least important of these three components.  By definition, it has no game effect.  However, playing a game is more than manipulating game elements; what really matters is the player’s experience.  That experience can be greatly affected by the setting material.  This is an opportunity that shouldn’t be neglected.  Of course, some players may be unwilling to read through a novel’s worth of text in order to play a game…I guess the trick is to create material that gets its point across quickly.  (You can always provide optional, longer versions—an in-game “encyclopedia”, for example—for those who are interested.)