The rules are simple, place all the numbers 1 through 9 in each row, column, and square. The resulting puzzles can be quite challenging.
The free version allows you to generate and play unlimited puzzles. You can choose from 10 levels of difficulty. ThirdEpic Sudoku helps you play better with an interactive tutorial and with visual hints. The registered version allows you to share your puzzles by saving them or printing them as well as loading games from your friends or the newspaper.