Resource
interface Resource
A Game is the root of a tree structure, with each node of the tree being an Resource. All of a games resources are stored within this tree.
I chose not to call this class Node to avoid confusion with Glok's Node class.
If the resource is a ParentResource (such as Game, Graphic and Folder), then it has child nodes.
If a Resource corresponds to a file (such as an image or a sound file), then it also implements the FileResource interface.