Sudoku

About Sudoku

Sudoku's modern form was designed in 1979 by American architect Howard Garns and published as Number Place. It was popularized in Japan in the 1980s by puzzle magazine Nikoli, which gave it the name Sudoku, and became a global craze after British newspapers started publishing daily puzzles in 2004.

A Sudoku puzzle is a 9x9 grid split into nine 3x3 boxes, partially filled with digits. The goal is to fill every empty cell with numbers 1 through 9 so that no digit repeats in any row, column, or box. Every proper Sudoku has exactly one solution, and reaching it is a pure test of logic.

How to Play

Controls: Click a cell and type a number from 1 to 9. Use the notes mode to pencil in candidate numbers. Press DELETE or 0 to clear a cell.

Objective: Fill every empty cell so each row, column, and 3x3 box contains all digits 1 to 9 exactly once.

Tips & Strategy

• Scan rows, columns, and boxes for a digit that already appears several times — it often locks a remaining placement.
• Pencil in candidates for tricky cells. Notes keep your logic visible instead of relying on memory.
• Look for naked pairs: two cells in a unit that can only contain the same two numbers — you can eliminate those numbers from the rest of that unit.
• Never guess on a well-formed puzzle. Every step should follow from a logical rule.
• When stuck, step back to easy logic. Most players get stuck by missing a simple scan.