Stress Free Sudoku Game Book is an iPhone game developed by Boy Howdy Technology LLC. It is a Sudoku game with 200,000 puzzles and five different difficulty levels. The game has a full version license and is completely free to download.

The game has an easy to read and beautiful number interface. It has a dual-keypad input system that is fast and intuitive, making it easy to mark answers or pencil marks. The pencil marks are auto-erased as you enter answers, and horizontal and vertical guidelines make it easy to look at your current row and column. The game also has an auto-highlight feature for other cells with the same number as the selected cell, cells that have a visible conflict, and pencil marks that have a visible conflict.

The game also has a hint function if you get stuck and a check your work function to spot any problems you might have. The game saves your progress automatically, so you can take a break and come back to it later. You can also listen to your own music while playing, and sounds can be disabled if you want a quiet game. Overall, Stress Free Sudoku Game Book is a great game for Sudoku lovers who want to play without any stress.