Sudoku – Play Online for Free
The rules of Sudoku are simple and easy to understand. And it is precisely that simplicity that makes finding the solution so demanding. Each Sudoku grid has only one correct answer, and the online version enforces the rules strictly. Two things are all you need: knowledge of the numbers 1 to 9 and the ability to think logically. The goal is to fill a grid of nine large squares, each divided into nine cells, using the numbers 1 to 9. The real challenge lies in the constraints you must respect and the difficulty level you choose. Four difficulty levels are available here.
How Sudoku Works
Whatever level you choose, every Sudoku begins with a partially filled grid. The pre-filled numbers serve as clues for working out which numbers are missing. On easier levels, many cells are already filled in. On "Very Hard", far fewer clues are given and the combinations are less obvious.
Three rules govern the entire game:
- Rows: Each horizontal row must contain the numbers 1 to 9 exactly once. The order does not matter.
- Columns: Each vertical column must also contain the numbers 1 to 9 without repetition.
- Blocks: The grid is divided into nine 3x3 blocks called nonets. Each nonet must also contain every number from 1 to 9, each exactly once.
In short: every row, every column, and every block must contain all nine numbers, each appearing exactly once. No arithmetic is involved; everything relies on logic and deduction.
Special features and aids
Pre-filled numbers appear in grey; numbers you enter are shown in blue. Any value can be erased at any time. Duplicates are immediately highlighted in red, which prevents the kind of hard-to-spot mistakes that can occur on paper. The Hint button automatically places one correct number in the grid. Complete Solution fills in the entire puzzle. Clear Cells empties the grid entirely, which is useful if you want to enter your own Sudoku to solve. Activating Show Help displays the logically possible numbers for each empty cell. If a cell shows no options, an error has been made somewhere and the grid cannot be solved in its current state. The virtual eraser is always there to help you backtrack.
More Brain Games and Relaxing Alternatives
Need a break from the logic? Try something with more action: Bubble Shooter or Battleship offer a completely different kind of challenge. For something quieter, Triple Spider Solitaire or Freecell Windows XP are meditative alternatives. If you enjoy demanding strategy games, Backgammon, Mahjong, Checkers, and Nine Men's Morris are all available here for free, with no download required.