The Rules of Sudoku
Sudoku is elegant because its entire structural depth comes from just three simple rules. There is no math involved—only elimination and logic.
The Three Golden Rules
Each horizontal row of 9 cells must contain the digits 1 through 9 exactly once.
Each vertical column of 9 cells must contain the digits 1 through 9 exactly once.
Each 3x3 subgrid (or "box") must contain the digits 1 through 9 exactly once.
Common Beginner Mistakes
- Guessing: The most common trap. If you guess, you will almost certainly break the board without realizing it until 10 moves later. Always use logic.
- Ignoring the 3x3 Boxes: Beginners often perfectly align a row and column but accidentally place a duplicate inside the encompassing 3x3 box. Remember to check all three intersections!
- Tunnel Vision: Getting stuck staring at one empty cell. If a cell is impossible to figure out right now, move to another section of the board. Answering other cells will eventually reveal the answer to the stuck one.
Frequently Asked Questions
Can a given number ever be changed?
No. The numbers permanently printed on the grid at the start of the game are the anchor points of the puzzle. They are required to find the unique solution.
How do I know I won?
When all 81 cells are filled mathematically perfectly obeying the three golden rules, Voku will automatically validate the board and trigger the Victory screen.
Need a refresher on UI mechanics? Read our How to Play Guide.
Ready to test your logic?
Start with an easy puzzle to practice the rules.