Jigsaw Sudoku vol. 4: 160 very twisted puzzles (Jigsaw Sudoku Books)

Jigsaw (or irregularly shaped) Sudoku puzzles share the same rules with classic Sudoku. The only difference is that the nine nonets are, well, irregularly shaped. This makes the puzzles slightly harder than the original Sudoku and surely more entertaining, because every puzzle has a unique nonet design and therefore, they can never become boring. In this book there are 150 of these puzzles in 5 levels of difficulty. For the hardest of puzzles you must use "The Law of Leftovers" solving method, which is explained in the introduction. In addition, an extra 10 SPECIAL Outside Jigsaw Sudoku puzzles are included. What they are is for you to discover!