Sudoku
Puzzle Games, Strategy Games · Updated
Sudoku is the number puzzle most people already know how to play: a nine-by-nine grid, nine boxes inside it, and the same nine digits in every row, column and box. This version runs in the browser with four difficulties, and every puzzle is generated when you start it, so nothing repeats.
How to play
Pick Easy, Medium, Hard or Expert, and the game deals a fresh grid. Tap or click a cell and enter a digit, or use the number row on a keyboard: 1–9 fills the selected cell, the arrow keys move around the board, Backspace erases, N toggles notes, H spends a hint and Ctrl/⌘ + Z undoes your last entry. Esc pauses, which also saves the board.
Wrong entries are marked in red and underlined, so a mistake is visible the moment you make it. Three mistakes end the round, but you get one second chance — which makes an early wrong number a warning rather than a disaster.
Scoring, saving and resuming
Score is time based: the sooner you finish a puzzle, the better the score, and the menu keeps a best score for each difficulty. The board is saved automatically while you play, so closing the tab is safe — when you come back, the same grid and the same clock are waiting. Pausing stops the clock, which matters if you are chasing a best score.
How to get faster
Two habits do most of the work. First, scan before you write: find the row, column or box that already has the most numbers filled in, because that is where the fewest candidates remain. Second, use notes properly — write candidates into every uncertain cell, then look for a digit that can only go in one place, or two cells in a box that can only hold the same pair. Guessing is the slowest way to finish a puzzle, and the mistakes you make while guessing are the ones that end the round.
Who it is for
Sudoku suits players who want a puzzle they can pick up for five minutes and come back to later: the autosave and the per-difficulty best scores make both habits easy. If you have never played before, start on Easy and finish a few boards before moving up — the difficulty levels change how much work the grid does for you, not the rules.
How to get a high score
- Start with the row, column or box that already holds the most numbers — the more you can see, the fewer candidates are left.
- Turn notes on before you guess. Sudoku rewards elimination, and notes keep a cell's candidates visible instead of remembered.
- Hints are worth mistakes, so spend them when you are genuinely stuck rather than on the first awkward cell.
- Three wrong entries end the game, but you get one second chance. Treat the red numbers as a warning rather than a loss.
- If two cells in a box can only hold the same two numbers, nothing else in that box can use them. That single observation unlocks a lot of hard boards.
Questions
How is the score calculated?
Score is time based — the faster you solve a puzzle, the higher it is. Each difficulty keeps its own best score on your device, and the game autosaves, so you can close the tab and resume the same board later.
Are the puzzles the same every time?
No. Every puzzle is generated on the fly and checked to have exactly one solution, so there is nothing to memorise and no grid you can learn by heart.
Does it work on a phone or tablet?
Yes. The layout adapts to the frame it is embedded in — side by side in landscape, stacked in portrait — and tapping a cell opens the number pad, so the whole game is playable without a keyboard.
Can I play it in Chinese?
Yes. The language button switches between English and Chinese, and your choice is remembered on the device. English is the default when you arrive from the site.
What do notes, hints and undo do?
Notes let you pencil in candidates without committing to them, hints fill in the correct number for the selected cell (three per game), and undo steps back through your entries. Erase clears a cell you filled in yourself.
