The Playground

The Playground is primarily a test and demonstration of our ability to build interesting characters that engage in reasonably complex social behaviors. These behaviors have to reflect the personality of the character, the emotional state of the character, and the relationship the character has with the other characters.

This is a simulation of 3 kids (one is the user) on a playground. Although they can engage in a number of different behaviors, one of their favorites is trading baseball cards.

Source: http://www.cs.cmu.edu/afs/cs.cmu.edu/project/oz/web/worlds.html#playground