CISRA Puzzle Competition 2013 - Hints

4D. XYZ-Word

• This crossword game needs to be considered in three mutually perpendicular directions.
• Words in the grid are numbered sequentially, running across, then down (like a regular crossword), then in. The grid is 9×9×9. The across/down planes have 180° rotational symmetry, like most regular crosswords. The across/in and down/in planes do not - for good reason.
• NOTREDAME, MOUSETRAP, and OPERA intersect in the middle of the cube. What shapes do the cubelets with letters in them form when viewed from each direction?