Not only does Simple Sudoku make challenging puzzles, it also provides tools to help solve them - removing the drudgery but not the fun. Keeping track of possible values for blank cells (candidates), providing filters and color markers are just some of the tools available to make solving even those really tricky puzzles possible. Also, if you ever get really stuck, Simple Sudoku can get you started again with a discrete hint (without giving everything away).

Download: Simple Sudoku 4.2i