Positive energy for the brain. 2 puzzles per page. 60 Killer sudoku puzzles 10x10 hard levels. 60 Killer sudoku puzzles 12x12 extreme levels. 60 Chain Sudoku 8x8 hard levels. 60 Chain Sudoku 9x9 extreme levels. Killer sudoku. This Sudoku leads step by step to the top of the skill. It is necessary to fill empty cells with numbers from (1 to 6; 1 to 8; 1 to 9; 1 to 10; 1 to 12), each of the digits should appear only once in each row and column of the 6x6; 8x8; 9x9; 10x10; 12x12 square. The sum of all the numbers in the cage must correspond to the number printed in the corner. They can be called figurative or geometric, they also have names (Killer Jigsaw Sudoku, Killer Geometry Sudoku, Killer Irregular Sudoku, Killer Kikagaku Nanpure). Chain sudoku ("Strimko", "Gyrus Sudoku") is a square consisting of circles. The goal is to arrange the figures in circles so that in each horizontal and each vertical all the numbers are different. In the links of one chain all the numbers must also be different. Unique puzzles. Only 1 verified solution. All answers are at the end of the book. Sudoku puzzles of hard and very hard levels have a lot of names: sudoku mania, games puzzle games, fiendish sudoku, sudoku junior, usa sudoku, sudoku au, puzzle g, the sudoku, sudoku uk, sudoku evil, sudoku kingdom, usa today sudoku, hard extreme sudoku puzzles, best sudoku, big sudoku, addicted, how to sudoku, the daily sudoku, sudoku billions, sudoku maker, sudoku c, how to solve sudoku puzzles, sudoku name, daily sudoku game, sudoku o, blank sudoku grid, sudoku on, sudoku today hard, sudoku sudoku, puzzled, sudoku competition, puzzle software, math sudoku, simple sudoku game, make your own sudoku, new puzzle, playsudoku, et puzzle, one sudoku, internet puzzles, sudoku game and answer, sudoku puzzle maker, sudoku cheat, how do i play sudoku, today's sudoku, a puzzle game, puzzle 200, games games sudoku, puzzle game puzzle game, play soduko, sudoku deluxe, sudoku logic, where can i buy sudoku puzzles, sudoku 1 9, more puzzle games, real sudoku, action puzzle games, sudokud, 1sudoku, play sudoku offline, sudukus, sudoku p, sudoku fill in, sudoku flash, g puzzle games, sudokupuzzle, s doku, js puzz, sudoku sudoku sudoku. I hope you enjoy the book. Best regards, Basford Holmes