Sudoku Classic
Play Sudoku Classic free online — solve endless Sudoku boards across three difficulty levels, fill every row, column, and 3×3 box. No download.
Strategy
Sudoku Classic
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📖 How to Play
Select an empty cell, then tap numbers 1-9 to place a value. Correct entries give points, mistakes cost lives. Reach 3 mistakes and the run ends. Clear boards quickly for time bonus and continue to the next puzzle.
❓ Frequently Asked Questions
How does scoring work in Sudoku Classic?
Each correct number placement earns points. Completing a full board gives a time bonus based on how fast you solved it. Chain multiple boards in a row for increasing score multipliers.
What happens when I make a mistake?
You have 3 lives per run. Each incorrect number costs one life. After 3 mistakes, the game ends. Correct placements are locked in permanently.
What difficulty levels are available in Sudoku?
Three levels: Easy (many given numbers), Medium (balanced challenge), and Hard (minimal clues). Each completed board advances to the next puzzle at the same difficulty.
How do I enter numbers — tap, keypad, or keyboard?
Tap a cell to select it, then tap the on-screen keypad — or just type digits on a physical keyboard on desktop. The keypad is thumb-sized for phones, and every entry is validated instantly against the 3-mistake limit.
What happens after I finish a board?
The run continues: a fresh board chains in and your score carries over, so one session can stack multiple completions. Faster solves earn bigger time bonuses — that is how high scores are built.
How many points do I get per cell and per board?
A correct digit scores 8 + min(24, streak×2). Clearing a board adds max(0, 160−seconds) plus 120 + level×15, then the next board at the same difficulty. Completing a board also refunds 1 mistake (not below 0). Wrong digits cost a life; 3 mistakes end the run. Emptying a cell resets streak and does not cost a life.
Are there pencil notes, and how many unique puzzles are there?
No notes mode — digits only, validated against the solution immediately. Each difficulty (Easy/Medium/Hard) has 3 built-in 9×9 boards that rotate. Free in the browser, one player, no download. Keyboard 1–9 or the on-screen pad.
What are the best Sudoku strategies for beginners?
Scan rows, columns, and 3x3 boxes for digits that can only fit one cell (hidden singles), and fill those first. Each locked digit unlocks more. Master Easy boards before moving up: they build the pattern recognition that makes Medium and Hard solvable, and fast Easy clears still earn time bonuses toward your run score.
Can I erase or change a number after placing it?
You can clear any filled cell, but it resets your streak bonus to zero — it never costs a life. Wrong digits are different: they are validated the moment you place them and cost a life instantly. So think before you tap: only commit digits you have verified against the row, column, and box.