If you are not a game designer:

Fun

(see also: Enjoyable, Cool, I Like It)

Something that I think is cool;

something that I imagine other people would think is cool, if a designer would just listen to my idea

If you are a game designer:

Fun

(see also: Blah Blah, Nice)

A completely meaningless term that should never be used;

except when describing the job responsibilities of a game designer to someone over 40

If you are a game designer writing about game design:

Fun

The positive emotion associated with fulfilling a common teleological aspiration

 (I realize this definition may itself need some explanation.)

Human Needs 

One way of understanding human behavior is to look at our needs.  If you assume that people are basically reasonable and that they are motivated to act in a way that fulfills their needs, then you can categorize different behavior based on the need that it satisfies.  The most well-known example of this technique is Maslow’s Hierarchy of Needs.  It’s like the Food Pyramid of human desires.  Unfortunately, neither the Hierarchy or the Pyramid are based on solid scientific research, so they tend to be misleading.

A more rigorous categorization of needs has been put forth by Edward Deci and Richard Ryan at the University of Rochester.  They have researched people’s need for self-determination, specifically their needs for competence, autonomy and relatedness.  They have even applied this theory to games with fascinating and practical results.  (If you are interested in this topic or their research, I recommend reading Why We Do What We Do: Understanding Self-Motivation.)

When our needs are being met, we describe the resulting emotion with a variety of terms.  Satisfying, Fulfilling, Relieving, Gratifying, Pleasurable, and Fun.  Each of these emotions is specific to the type of need that is being met, so if we can determine which kinds of needs result in fun we will be closer to defining the word, and have a greater understanding of our goal as designers.

The Need for Fun?

An immediate objection springs to mind against linking fun to needs.  Despite what you told your mom when you were a kid, you can’t die from fun deprivation.  How can fun be related to needs if you don’t actually have to have it to survive?  Well, psychology doesn’t make a distinction between needs and wants, in fact a better term might be desires or appetites.  However, this does bring up an important distinction that will help narrow down what sorts of needs result in fun when they are satisfied.

Some needs produce a negative emotion when we lack them, but are virtually forgotten once met.  These needs are requirements.  Carbohydrates, for example, are a requirement.  If you don’t have any, you will experience wracking hunger pangs, but if you have a sufficient supply you no longer think about them.  Other needs are just the opposite.  When these aspirational needs are not met, they rarely bring themselves to mind, but when they are fulfilled we experience a strong positive reaction.  Pancakes, for instance, are an aspirational need.  Nobody suffers greatly when pancakes are not available, but everyone enjoys them if given the opportunity.

Having made this distinction, it’s clear that fun is the result of satisfying an aspirational need.  Much like pancakes, fun experiences are not required for survival, but we still enjoy them when they are offered.  However, this category is still too broad.  Pancakes are delicious, but not necessarily fun.

The Need for Greek?

One characteristic that is unique to fun experiences is that they require participation.  Many needs can be met by an external source, the way a mother provides for the needs of a baby.  These kinds of needs are often physical objects: food, water, a place to live, a large screen TV.  But they can even be psychological needs like the desire to have the respect of one’s peers, or the need to know how something works.  These needs are ontological needs, meaning they are ends in and of themselves, they exist for the person.

Needs that result in fun are very different.  One person cannot play or learn or rest for another person; they must do it for themselves.  These teleological needs are met when we allow ourselves to be the means for some purpose beyond ourselves.  That purpose may or may not be useful; work can be as fun as play, even though it also provides for many other needs.  They key component is participation.

Every individual values needs differently, but with both of these axis we can arrange all needs into four quadrants: 

The Need for a Conclusion

Now we have a sufficiently narrow range of needs that result in fun, specifically those in the upper-right quadrant.  These needs are aspirations because we get a positive emotion when they are met, but do not necessarily suffer when they aren’t, and they are teleological because they allow us achieve some potential end and require our participation.

It remains to be seen if this will prove itself to be a useful definition, but at least it is more specific than “I know it when I see it.”