The basis of this puzzle, is based on a common 2D chess puzzle, where you try to fit 8 queens on a chessboard without the queens being able to attack each other.
Extend this concept into a 3D cube (8x8x8... like 8 chess boards on each other), but we do analysis on both vertical and horizontal planes. So no queen can attack each other in any vertical plane or in any horizontal plane.
What is the maximum number of queens can you fit into this chess cube without them being able to attack each other. (To describe your solution, feel free to post an image showing each layer in order, or illustrate it with text of x's and o's)