Mini Jigsaw Sudoku - 200 Easy Puzzles 6x6 (book 1) - Liam Parker - Bog

The rules of Jigsaw Sudoku are similar to standard Sudoku, since you must place each of the numbers 1 to 6 (or 1 to whatever the size of the puzzle is) into each of the rows and columns. However whereas standard Sudoku also has rectangular boxes that must each contain every number, in Jigsaw Sudoku these boxes are replaced by different bold-lined shapes that must each contain every number instead.