Definition of an abstract class in the game.
The concept of abstract class is considered in the Greenfoot Environment and Java programing language. In the context of game development, the PassiveActor class is a blueprint for acting. Therefore, it is defined as an abstract class and established as the ancestor of the Orb and Direction classes, making Orb and Direction its descendants. Since the act() method is already defined in the PassiveActor class, it should be removed from the Orb and Direction classes.