Doodle CubHow to play Doodle Sudoku
- Pick a tier and press Play, or play today's Daily. The clock starts on your first entry.
- Fill every row, column and 3x3 box with the digits 1 to 9, each once.
- Write a digit straight into a cell with your finger, pen or mouse. Write big for an answer and small for a pencil mark; scribble back and forth to erase. If it misreads you, tap the right digit in the bar under the grid.
- Prefer typing? Select a cell and use the number pad or keys 1–9. Turn on Pencil (or hold Shift) for pencil marks.
- Stuck? A hint names the technique and shows the cells to look at, without filling a digit. It adds 30 seconds, and you get three per puzzle.
- In Strict mode every entry is checked: three mistakes and the puzzle is over, but a Strict solve scores 25% more.
About this game
Doodle Sudoku is classic 9x9 sudoku on a clean notebook page, where you can write your answers by hand. Your own strokes are read on the spot, inside the game, and kept in ink on the grid; the number pad and keyboard work too. Every puzzle has exactly one solution and is graded by the hardest technique a human solver needs: Warm-up needs only singles, Solid needs pairs, Sharp needs pointing pairs and box-line reduction, Expert needs X-wings and triples, and Fiend needs XY-wings, simple colouring or swordfish. Expert opens after five Sharp solves and Fiend after five Expert solves. A new Daily puzzle arrives each day, easy on Monday and hardest on Saturday, with a streak and a 30-day calendar. Beat your best and your average of the last ten on each tier, unlock new inks and a night page as you solve, and teach the reader your handwriting in Calibrate. If you reload by accident, your puzzle comes back paused.
Controls
| Keyboard | Touch |
|---|---|
| 1–9Enter a digit in the selected cell | Write it in the cell with your finger, or tap a cell and a number key |
| Shift1–9Pencil mark (or Space to lock pencil) | Write it small, or turn on Pencil and tap a number key |
| ←↑→↓Move the selection | Tap a cell |
| BackspaceErase (right-click also erases) | Scribble over it, or the Erase key |
| ZUndo | Undo button (or a two-finger tap) |
| HHint (+30 s) | Hint button |
| PEscPause and resume | Pause button |
| EnterNext puzzle | Next puzzle button |
On a phone or tablet: Write a digit in a cell with your finger: big for an answer, small for a pencil mark, scribble to erase; strokes may spill past the cell. Or tap a cell and a number key. Pencil, Erase, Undo, Hint and Pause are buttons on screen (a two-finger tap also undoes). Turned sideways, the tools sit in a strip by the board. The touch layout follows how you play, on any screen (touch laptops too): it comes in at your first finger and goes at your next key press; the pause card has On-screen controls (Auto, Always, Off), Left-handed (mirrors the sideways strip) and Vibrate.
Questions
Is Doodle Sudoku free?
Yes. It is free to play in your browser, with nothing to download and no sign-up.
How does handwriting work?
Draw a digit in a cell. It is read straight away on your device, with no internet needed. Strokes taller than about half the cell become an answer; smaller ones become pencil marks. If a digit is misread, tap the right one in the bar under the grid, and use Calibrate in the pause menu to teach it your style.
How are the difficulty tiers decided?
Each puzzle is solved by a technique solver that always uses the simplest step available. The hardest technique it needs sets the tier: singles for Warm-up, pairs for Solid, pointing pairs and box-line reduction for Sharp, X-wings and triples for Expert, and XY-wings, simple colouring or swordfish for Fiend. Every puzzle has exactly one solution.
What do hints cost?
Each hint adds 30 seconds to your time and you get three per puzzle. A hint names the technique and highlights the cells involved, such as "Hidden single in row 4", but never fills in a digit for you.
What is Strict mode?
In Strict mode every digit you enter is checked against the solution. A wrong digit counts as a mistake and three mistakes end the puzzle. Strict solves score 25% more points and get a Strict stamp.
What happens if I reload the page?
Your current puzzle, including your written digits and pencil marks, is kept for this browser tab and comes back paused. Best times, unlocks and Daily results are saved in this browser.
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