MySudokuGuru Lite is a free program which not only enables you to play Sudoku on your iOS device but will also explain how to solve each Sudoku if you get stuck! The app has the following features:
. 6 levels of difficulty.
. Use pencil marks to help solve the more difficult Sudokus.
. Ask for help - the program will give you a hint or will solve the whole Sudoku.
. Get a step by step explanation of the logic used to solve each box.
. Full undo history so you can backtrack through your game.