Space Invaders Class Diagram, Iteration 1

I am beginning the Space Invaders project the same way I begin every project -- with a rough class diagram to start getting some ideas down. It needs a lot of refinement, but it's a start.  At this point, I foresee uses of the Factory, Facade, Observer, and possibly the Template Method pattern, with probably more to come.

A first attempt at a class diagram for the Space Invaders project.