Sudoku — Play Free Online

What is Sudoku?

Sudoku is a classic logic-based puzzle game, presented here in the Sudoku Plus edition. The objective is to place digits into a nine-by-nine grid so that every row, column, and three-by-three block contains all numbers from 1 to 9 without repetition. It runs entirely in your web browser with no download or installation required.

Key features

• Clean interface: A clear nine-by-nine grid with highlighted active cells and selectable numbers.
• Multiple difficulty levels: Choose Easy, Medium, Hard or Extreme puzzles, or take on the Daily Challenges.
• Dual input options: Place numbers using your physical numeric keys or the on-screen digital panel.
• Assistance tools: Use pencil notes, undo, erase and an in-game hint when you need help spotting the next logical placement.
• Timer, score and mistakes: Track your time and score, and optionally play with a limit where more than 3 mistakes ends the puzzle.
• Cross-platform access: Play smoothly on desktop computers, laptops, tablets, and mobile phones.
• Pure deduction: Solve boards entirely through methodical elimination without arithmetic or guesswork.

How to play

1. Select your preferred difficulty setting to load a fresh puzzle board.
2. Examine the pre-filled starter numbers across the nine-by-nine grid.
3. Click or tap an empty square to highlight the tile you want to solve.
4. Use the number keys or tap the on-screen panel to input a digit from 1 to 9.
5. Check intersecting rows, columns, and three-by-three blocks to eliminate impossible placements.
6. Fill every remaining blank tile correctly to complete the board.

Controls

Action	Keyboard / mouse	Touch
Select tile	Mouse click	Tap cell
Input number	Number keys 1-9	Tap on-screen panel
Erase number	Backspace or Delete	Tap Erase
Notes, undo, hint	Click the Notes, Undo or Hint button	Tap the button

Grid structure and deduction rules

Every standard puzzle layout consists of eighty-one individual squares arranged into nine horizontal rows, nine vertical columns, and nine smaller three-by-three boxes. Each digit from 1 to 9 must appear exactly once in each row, once in each column, and once inside each three-by-three block.

Because no digit can repeat within its row, column, or block, placing a single number immediately narrows down the options for neighboring cells. Successful solving relies on systematically tracking these overlapping constraints across the entire layout.

Tips and strategy

• Scan crowded sectors: Start by inspecting rows, columns, or blocks that already hold most of their numbers, as finding the final missing values requires minimal elimination.
• Cross-reference lines: Follow a single digit across parallel rows and columns to identify which cell in an adjacent box must contain that value.
• Look for single candidates: Identify cells where eight of the nine possible digits are already present in the intersecting line or block, leaving only one valid choice.
• Avoid blind guessing: Placing unverified numbers can cause errors that break later deductions; switch on Notes to pencil in candidates instead.
• Use hints when stuck: Take advantage of the built-in hint feature to reveal a valid placement when you reach a difficult standstill.

Similar games

If you enjoy logic puzzles, try Minesweeper, where number clues reveal hidden mines, 2048 for number-merging strategy, or Tetris for fast spatial puzzling. Guess Who? offers another calm game of deduction.