First, nice game. Simple, and enjoyable. I have a question with regards to your choice in coding. (I am pretty new to this, so I'm sure there's a good answer, I just don't readily see it.) Why did you create a new class DoubleRectangle, and have enemies inherit from it, instead of having enemies inherit from Rectangle the way Player does? I guess it gives you the ability to have the enemies exist sort of between pixels, but their position gets rounded in the cast to int anyways, so do you gain a lot by doing it this way?