Warning: IdeasI’m excited about the following post, not because it is especially insightful, but because it features this blog’s first interactive example! Games are so dependent on interactivy, it’s virtually impossible to explain certain key concepts without some kind of playable demonstration. Sometimes I need to make my point about game design with a game! To that end, I’m teaching myself Actionscript so I can make my own little illustrative experiences. I probably won’t have time to create too many of these, but this one was a lot of fun to make, and I hope you like it. (I’m still trying to come up with a good portmanteau…  Game-onstrations?  Exam-plays?)

I also registered a new domain, so now you can find this blog at  (Some PR firm is squatting on the article-less version.)  Old links will still work, but this url is more memory friendly.

Definition: Game Mechanics

Game Mechanic

A single constraint on the possible gameplay actions that determine a part of the player’s experience.

According to our working definition of gameplay, the purpose of a game mechanic is to constrain a game’s interactivity so that it guides the player toward a fun experience.  Tuning these contraints is one of the most important game design processes.  However, in order to tune game mechanics, it is necessary to understand what mechanics are and how they combine to form gameplay.

First, let’s look at how a single game mechanic constrains the possible actions a player can take.  Often these constraints are explicit rules like “If the King is put in check and cannot legally escape, the king is checkmated and the game ends in a loss for that player.”   Sometimes they are limits enforced by the simulation; there are some gaps that Mario can only jump while running.  The most important constraints are usually determined by the game’s control scheme.  After all, the player can only perform actions which are mapped to available inputs.

Another common type of constraint is the player’s objective in the game.  For instance, a goal in Pac-Man is to eat all the dots.  This limits the player’s behavior because any interaction that does not involve eating dots is irrelevant to the game.  This mechanic divides all the entire spectrum of possible actions the player can take into two halves, actions that are permited and those that are prohibited.

More DoTs!  More DoTs!

Pac-Man suffers from OCD

Game mechanics guide the player experience by removing some alternatives and emphasizing others, but by itself, a single game mechanic is not a game and cannot lead to a fun experience.  In fact, a single game mechanic by itself is barely even interactive.  With only one constraint, there is only one option.  There is no room for choice or skill or expression.  To demonstrate this point, I built a “game” based on a single dot-eating game mechanic.


(My free Flash host can no longer keep up with demand, please click this link to load the example.)

In order to actually define an experience, game mechanics must be placed in opposition to one another, much like the legs of a tripod.  That way instead of creating a single boundary (and therefore no choices) they create a region of interactivity for the player to operate within.  This is what Will Wright calls a possibility space.  It is the sum of all the potential gameplay experiences, sort of the wave function of game design.
Triangle Man hates Pac-Man, they have a fight, Triangle wins

Or maybe the Triforce of Game Design?