Building should include the concept that, in this context, actor refers to any playable or nonplayable object that interacts with other objects in the game (e.g., the actor could be a human, a spaceship, a ball).
Process/Skill Questions:
What is an actor, and what is the difference between a playable actor and a nonplayable actor?
What are some examples of playable actors and of nonplayable actors?
What interactions can occur between actors? Provide examples.