http://www.graycode.com/contact.htm and is a totally free puzzle app.
Are you familiar with Nonogram? It's a 2-dimensional game where you have to color in some numbers on a grid via vertical/horizontal clues. They're fun, but I've never actively sought them out.
NonoCube is essentially the same idea, but in 3 dimensions. You must create a shape. To do that, you will 'shield' the boxes you want. And 'bomb away' the boxes you do not. What about the boxes inside that you cannot access?
NonoCube is a winner. Download it.