Brain Teasers
- 121
- Sudoku123.ca
- A set of rules applicable to a regular Sudoku, that allows 2 to 5 players solve a single puzzle, and compete for points. [English/Français]
- 123
- Sudokuto
- Two-player variant. Offers several board sizes to play against the computer. This site has many other Sudoku variations (e.g., Wordoku, 3D Sudoku, Calcudoku, Greater Than Sudoku, etc.) [English/Norsk]
- 125
- Online Calcudoku Puzzles
- Daily Calcudoku (sizes 4x4 to 12x12) puzzles which can be solved for points.
- 126
- Daily Killer Sudoku
- Daily killer and greater-than killer sudoku puzzles that can be played online or printed.