How to play Sudoku Patch
The rules
A solved 9×9 sudoku was cut into its nine 3×3 boxes, and the boxes were shuffled into a tray. Put every box back into one of the nine slots of the grid so that:
- every row holds the digits 1 to 9 once;
- every column holds the digits 1 to 9 once;
- every clue digit (a small digit in an empty slot) matches the digit of the box you place there.
Boxes cannot turn or flip. Every puzzle has exactly one answer, and logic alone is enough to reach it. You never have to guess.
How to play here
- Drag a box from the tray onto a slot. Drop it on a filled slot to swap, or drag a placed box back to the tray.
- Tap: tap a box to pick it, then tap a slot. Tap a filled slot to pick its box, and tap the tray to send it back. Tap the picked box again to cancel.
- Keyboard: Tab to a box, Enter to pick it, the arrow keys to choose a slot, Enter to drop. Escape cancels. Delete sends the box in a slot back to the tray.
- Undo and redo: Ctrl+Z and Ctrl+Y (on a Mac: ⌘Z and ⌘⇧Z).
- Hint: each press of Hint tells you more: first where to look, then which technique works there, and finally which box goes where. If a box is in the wrong slot, the hint shows you where.
A digit that repeats in a row or column, or a box digit that does not match a clue, is marked with stripes and a wavy underline.
Difficulty levels
The level is set by the hardest technique the puzzle requires:
| Level | Techniques required |
|---|---|
| Easy | Clue match, only one box fits (6 clue digits) |
| Medium | + One place only, pairs |
| Hard | + Finish the band |
| Expert | + Fill the empty band |
Easy puzzles have 6 clue digits, so they are easy to start. Harder puzzles have only 2 to 4.
Techniques
Clue match
Only one box in the tray has the clue digits of a slot in the right cells. It goes there.
Only one fits
Every other box would repeat a digit in a row with a box beside the slot, or in a column with a box above or below it. The last box goes there.
One place only
A box fits only one of the empty slots. It goes there.
Pairs
Two slots can only take the same two boxes. Those two boxes go nowhere else. It works the other way round too: two boxes that fit only the same two slots take those slots.
Finish the band
A row of slots (a band) has two empty slots left. If putting a box in one of them leaves no box that completes the band’s rows with nine different digits, that box does not go there. The same works for a column of slots (a stack).
Fill the empty band
The same reasoning for a band or stack with all three slots empty: a box is ruled out of a slot when no pair of the remaining boxes can complete the other two slots.
Tips
- Start with the clue digits. A slot with two clues often has only one box that matches.
- Compare the rows of two boxes before you put them side by side: they cannot share a digit in the same row.
- When one band is complete, the boxes left for each other band are limited by the columns too.
FAQ
- What is different from normal Sudoku?
- You do not write digits. The grid is already solved, but it was cut into its nine 3×3 boxes and shuffled. You move whole boxes back into the grid so that every row and column holds 1 to 9 once.
- Can I turn a box?
- No. Boxes cannot turn or flip. Each box goes into a slot exactly as it is shown in the tray.
- What are the small digits in the empty slots?
- They are clues. The box you put in that slot must have the same digit in the same cell. Without them, several arrangements would work, because two whole rows of boxes can always trade places.
- Is there a new puzzle every day?
- Yes. A new Sudoku Patch is published every day at each of the four levels: easy, medium, hard and expert. Earlier puzzles are in the archive.
- Do I need an account to play?
- No. You play right in your browser, with no sign-up and no cookies. Your progress is saved in your browser.