Hard Core 16x16 Sudoku 200

Mastered 9x9? Hard Core 16x16 Sudoku 200 is the next step. These Mega Sudoku use the numbers 1 to 16 on a grid of 256 squares, divided into sixteen 4x4 boxes, and there are no easy puzzles at all: 100 are Hard and 100 are Very Hard.

On a grid this size, every technique you use on 9x9 still works, but there's far more to keep track of. Each row, column and box holds sixteen numbers, so candidate lists are longer and each solve takes longer. That's the appeal: one puzzle gives you a long, satisfying session.

The book has two puzzles per page, with the rules at the front and the solutions in the back. It's printed at 8.5 x 11 inches.

If you'd like to warm up on 16x16 grids first, 300 16x16 Mega Sudoku offers three difficulty ranges, starting with Easy to Hard. For a different kind of big puzzle, try Hard Core Samurai Sudoku 200, which joins five 9x9 grids into one.