Sudoku

Our Verdict

The cleanest pure-logic puzzle on the internet — no language barrier, no guessing required on well-formed puzzles, and difficulty scales precisely to your skill level. Better than crossword for players who prefer deduction over vocabulary.

How to Play Sudoku

1. 1Examine the pre-filled clue numbers — each digit already placed is fixed and cannot change.
2. 2For each empty cell, determine which digits 1-9 are still possible given what appears in the same row, column, and 3x3 box.
3. 3Use pencil marks (small candidate digits in the corner of a cell) to track possibilities when a cell has multiple options.
4. 4Apply elimination: if a digit can only go in one cell within a row, column, or box, place it there.
5. 5Work iteratively — each confirmed digit eliminates candidates in related cells, often unlocking new placements.
6. 6On harder puzzles, look for patterns like pairs (two cells in a unit that can only hold the same two digits) to make progress.