Sudoku

Sudoku.com is a free online sudoku game offering classic, killer, storybook and postcard puzzle modes across difficulty levels from easy to expert, plus master and extreme settings, daily challenges, a tournament mode and printable puzzles. Hints explain solving methods to help players improve, and each puzzle shows the percentage of players able to solve it. The game is developed by Easybrain and available in multiple languages including English, Japanese, Italian, Chinese, German, French, Spanish, Portuguese, Turkish, Polish, Korean, Thai, Vietnamese, Arabic and Russian.

The site states that ads help keep the game free.