What is Sudoku?

It's big in Japan, huge in Europe and sweeping America. Now, Sudoku (Japanese for "single number") lands in the Chicago Sun-Times.

• Sudoku for May 16

• Sudoku for May 15

• Sudoku for May 14

• Sudoku for May 12

• Sudoku for May 11

• Sudoku for May 10

For tips and solutions visit www.sudoku.com