You want to create multiple objects in a game which need to be rendered and interact with each other. However you are finding that your various game objects share most of the same information and behavior.

The entity pattern describes an interface to encapsulate the properties and behavior common to all game objects. For example, in almost every game the game objects have a position and dimensions to keep track of. Additionally, game objects generally need to perform a set of common operations such as render and update.

• Abstract Entity
• EntityGroup

You could also consider adding a unique id to the entity and a corresponding getID() method. — aschearer 2008/07/01 09:05

The obvious benefit of adopting the entity pattern is to consolidate behavior into a top level class thus reducing the amount of code you have to write to introduce new objects. On top of that, by making game objects conform to a single interface you greatly reduce the barrier to adding distinct game objects to your game. Finally when each of your game objects implement a single class you can employ the proxy pattern and implement a EntityGroup.

If you aren't careful you can end up pushing a lot of behavior into this interface. You'll know this is happening when you leave many methods unimplemented in concrete classes. When this happens it's probably a sign that you should adopt more than one top level interface.