PIENSALIA / ILLUSTRATED GUIDE
How to play Sudoku
Learn to read rows, columns, and boxes, then solve step by step with logic. Sudoku uses numbers 1 through 9: no calculations are needed.
Everything starts with three dimensions.
A cell belongs to a row, a column, and a 3 × 3 box at the same time. Always check all three units before placing a number.
Row, column, and box
The guide shows how the three units cross around one cell.
Three rules. No calculations.
Every row, column, and box must contain numbers 1 through 9 without repeats.
The most common mistake
Check the box, row, and column before confirming a placement.
Project. Eliminate. Place.
Scan rows and columns to reduce possible positions inside a box.
Eliminate by rows
Remove positions already blocked by a number in the same row.
Eliminate by columns
Remove positions blocked by the crossing columns.
Combine row and column
The intersection left after both checks is the forced position.
Let the pencil think with you.
Notes store provisional candidates. Remove them when a related placement rules them out.
When the first clues are not enough.
Single candidate
Place the only candidate that survives all three unit checks.
Naked pairs
Reserve two shared candidates for two cells in one unit.
Locked candidates
Use a box-line interaction to remove candidates from crossing units.
Which number is missing?
This box contains 1, 8, 3, 4, 2, 7, 5, and 9. The only remaining number is 6.
Choose your next game.
Frequently asked questions
Is Sudoku free?
Yes. You can play for free without creating an account.
Can I play on mobile?
Yes. The board and controls support touch screens and keyboards.
How does the daily challenge work?
The board is fixed by the UTC date and selected difficulty.