About this game
Fill 1-9 without repeats, the brain number puzzle
What this game is
Fill the blanks of a 9×9 grid with the digits 1 to 9. No row, no column and no 3×3 box marked off by the thick lines may hold the same digit twice.
A new grid is built every time you arrive. A complete solution is drawn first, then cells are emptied one by one, and a cell only stays empty if exactly one solution still remains. Nothing ever comes down to a guess, so every board is solvable by reasoning alone.
How to play
- Difficulty is how many blanks
- Easy, medium and hard differ by how many cells start empty. Fewer clues means looking further ahead to pin down a single cell.
- Tap a cell, then the pad
- Tap an empty cell, then pick a digit from the pad below. The erase key clears it, the printed clues stay locked, and on a desktop the number and arrow keys do the same job.
- Clashes turn red on the spot
- Put the same digit twice in a row, a column or a box and both cells turn red. You never have to hunt for a mistake after filling the grid in.
- The selected cell lights its lines
- Select a cell and its row, column and box light up together, with every copy of the same digit marked. It makes scanning for the blocked spot quick.
Frequently asked questions
- Can a board have more than one answer?
- No. A cell is only emptied after checking that exactly one solution remains, so every board has a single answer.
- Is there a hint button?
- There is no button that hands you an answer. Clashing digits show up in red right away instead, and the erase key lets you rewrite anything.
- Does it cost anything?
- It is free. One Google sign-in, then you pick a level and start.
- Is it awkward to solve on a phone?
- The number pad sits right under the grid, so a phone fills in one-handed. There is no app to install.
