How to Play Sudoku — The Number Logic Puzzle
Sudoku is a 9×9 grid puzzle invented in modern form in the 1980s and popularised worldwide by Japanese publishers in the 1990s. The rules are simple: fill in every cell so that the digits 1 through 9 appear exactly once in each row, each column, and each 3×3 box (also called a "region" or "nonet"). No arithmetic is required — Sudoku is pure deductive logic.
The basic rules
- A standard Sudoku grid has 81 cells, organised in 9 rows, 9 columns, and 9 boxes.
- Some cells start filled in. These are clues (called "givens").
- Your job is to fill the empty cells so each digit 1–9 appears exactly once in every row, column, and box.
- Every well-formed Sudoku has exactly one solution.
Solving techniques in order of difficulty
1. Naked Single
A cell where only one digit could possibly go — every other digit already appears in its row, column, or box. The simplest technique and the only one needed for easy puzzles.
2. Hidden Single
A digit that can only fit in one cell of a row, column, or box, even if that cell has many candidates. Find them by scanning one digit at a time across all units.
3. Naked Pair / Triple
Two cells in the same unit share exactly the same two candidates. Those candidates can be removed from every other cell in that unit.
4. Pointing Pair
A digit can only appear in one row of a 3×3 box. That means it can't appear in that same row outside the box. This eliminates candidates in neighbouring boxes.
5. X-Wing and Swordfish
Advanced techniques for hard puzzles. They look at a single digit across multiple rows and columns to find forced placements.
If you master the first three techniques, you can solve most easy and medium puzzles in 10–15 minutes. The hard puzzles in this game may require pointing pairs and naked pairs.
A scanning strategy that works
- Pick the digit with the most clues already placed (often 1, 5, or 9 depending on the puzzle).
- Scan every 3×3 box. For each box, ask: "Where can this digit go?" If only one cell, place it.
- Move to the next digit and repeat.
- After one full pass, every easy single will be filled. Restart with technique 2 (Hidden Singles).
Why Sudoku is good for your brain
Studies on cognitive aging suggest that regular puzzle-solving (Sudoku included) helps maintain working memory and attention. Even 10 minutes a day measurably improves pattern-recognition speed over a few weeks. It's not magic — it's just exercise for a part of your brain you rarely use otherwise.
