Rules
Fill the 9×9 grid with the digits 1 to 9 so that:
- every row has each digit once,
- every column has each digit once,
- every bold 3×3 box has each digit once.
The starting digits are fixed. Every puzzle here has exactly one solution, so it can always be solved by logic alone, without guessing.
Controls
- Tap an empty cell. Its row, column and box are shaded.
- Tap a digit on the pad to fill it in. The small number under each digit shows how many of that digit are still missing.
- Not sure yet? Turn on Notes to pencil in candidates. Placing a correct digit clears it from the notes in the same row, column and box.
- Wrong digits turn red right away and count as a mistake. Stuck? Hint fills one cell for you.
On a computer, type 1–9 to fill, 0 or Backspace to erase, use the arrow keys to move and press N to toggle notes.
Daily puzzle and challenges
The Daily puzzle depends only on the date (Korea time) and difficulty, so everyone gets the same grid that day. When you finish, share the link: your friend gets the same puzzle and sees how their time compares with yours. Want more? New puzzle makes a fresh random grid.
| Level | Starting digits | Good for |
|---|---|---|
| Easy | 38 | First-timers or a quick break |
| Medium | 30 | Using notes, about ten minutes |
| Hard | about 25 | Careful candidate elimination |
Your current game and best times (hint-free solves only) are saved in this browser only, so you can close the tab and pick up where you left off. For a test of pure speed, try the Reaction Time Test.