for the Sudoku fans out there....
Sudokube is the first to offer a true three dimensional Sudoku puzzle.
There are plenty of offshoots and variations of Sudoku out there, but none of the others are truly 3D, where the puzzle dives inside the 3D cube. Many place flat Sudoku puzzles on the surface of a cube.
Others are fully 3D, but do not follow the classic Sudoku rules, such as requiring that each row, column, and square contain unique values.