To play means to learn.
Through play you improve usability and UX
Each game is, by definition, a safe space where you learn things. That’s why we believe that a ludic mood enhances the usability of an application.
A game produces Flow.
When you play, you are deeply involved
With play you can obtain a better focus toward a goal. Users will be appealed each time they will discover a feature of the application, and they will use it in a more complete and deep way.
read the full extract at: http://playfuldesign.org/