Sudoku Japanese puzzle game played by placing numbers in a grid so that each number only appears once in each row, column, and region. Offers three difficulty levels.
Top Notch Su Doku Offers several web-based alternatives, including Worduku, code-duku, and Samurai sudoku. Also offers a web-based solver.
Sudoku League League of online competitors. Scoreboard, rules, FAQ, hall of fame, and instructions. [English/Czech]
Number Logic Offers a new timed game daily, with a validator and four difficulty levels.
Sudoku Prime Offers three difficulty levels and the ability to play against other players. [Requires Shockwave]
Web Sudoku Free puzzles with difficulty levels ranging from easy to evil. Provides print and online syndication.
Sudoku Central Offers daily puzzle for printing. Also includes archive, online solver, and solving tips.
Sudoku Hints Offers daily web-based puzzles with five difficulty levels. Includes solver, helper, and XML feed.
Sudoku by Froggy Generates 2x2, 3x3, and 5x5 puzzles with adjustable level of difficulty.
Play Sudoku JavaScript-based Sudoku, available for syndication on other sites.
Su-Doku.net Offers daily puzzle, downloadable games, and instructions.
Play Sudoku Registered users can save unsolved puzzles and high scores are kept at three difficulty levels. Also offers rules and tips for solving. [English/Russian/German]
BrainBashers Offers daily puzzle in one of three difficulty levels. Archive of daily puzzles and an assistant.
Daily Sudoku Puzzle Offers daily timed puzzle and four difficulty levels. [English/Portuguese/Spanish/German/French/Italian]
Sudoku Puzzles Daily puzzles offered at four difficulty levels, available for play online or printed out. Includes rules and archives.