Sudoku
Sudoku is the classic 9×9 number puzzle: every row, column and 3×3 box must hold the digits 1 to 9 exactly once. Play it offline in Cerebrum, the puzzle games app by Synapgeek, on iPhone, iPad and Android.
How to play Sudoku
The grid has 81 cells, grouped into nine boxes of 3×3. Some cells already hold a digit. Those are your starting clues and they never change.
Your goal is to fill the empty cells so that each row, each column and each box contains the digits 1 to 9 with no repeats.
In Cerebrum, tap a cell, then tap a digit on the pad. To jot down several possibilities in one cell, switch on Notes before you tap the digits.
Every digit is checked the moment you place it. A wrong digit costs you a mistake, and the third mistake ends the game. You win when the whole grid is correct.
Stuck? The Hint button shows the next step of the reasoning: it explains the technique step by step, then reveals the digit.
What Cerebrum adds to Sudoku
Sudoku in Cerebrum is the classic 9×9 grid, with no variants. You move up a path of levels in the difficulty you choose. Finish the path of a difficulty and Endless Mode opens, serving fresh grids one after another.
Four buttons sit under the grid: Undo, Erase, Notes and Hint. Duplicates are highlighted, your notes clear themselves from the related cells when you place a digit, and a key on the pad greys out once all nine of its correct digits are in place.
A hint does more than hand you the answer: it shows the next step of the reasoning and names the technique behind it, so the next grid feels easier. Some advanced techniques remove the impossible candidates from your notes instead of placing a digit. When a hint needs your notes, Cerebrum offers to fill them in for you.
Three mistakes end the game, but you can carry on with the same grid up to twice, with two hearts back each time.
Finish with no mistakes for three stars, one mistake for two, two or more for one. Hints do not count against your stars. The score rewards a quick, clean grid with few hints, and the difficulty multiplies it.
Daily challenge: pick Sudoku and the app sets the day's grid on Easy or Medium, the same for every player.
| Difficulty | What changes |
|---|---|
| Easy | 40 to 45 digits given. Open from your first launch. |
| Medium | 34 to 38 digits given. Open from your first launch. |
| Hard | 28 to 33 digits given. Opens as you progress through Medium. |
| Elite | 24 to 28 digits given (up to 29 in Endless Mode), on grids that call for more advanced reasoning. Opens as you progress through Hard. |
Tips to play Sudoku better
- Start by scanning. Pick a digit that already appears often, note the rows and columns that contain it, then look in each box for the one cell where it can still go. Move on to the next digit.
- Look for naked and hidden singles. If a cell's row, column and box already rule out eight digits, only one is left, so place it. A hidden single works the other way round: a digit that has only one possible cell in a row, column or box, whatever else that cell could hold.
- Do not guess: every digit is checked at once, and three mistakes end the game. When scanning runs dry, turn to notes and write the candidates for the most constrained cells. Cerebrum clears notes from the related cells each time you place a digit, so they stay up to date on their own.
- Naked pairs unlock hard grids. If two cells in the same row, column or box both hold only the same two candidates, those two digits belong to them: remove them from the notes of every other cell in that row, column or box.
Sudoku in Cerebrum: frequently asked questions
How are stars earned in Sudoku?
Only mistakes matter. A clean grid earns three stars, one slip earns two, and anything beyond that earns one. Hints never reduce them.
What are Notes for?
Switch on Notes to jot several candidates in one cell. Each time you place a digit, Cerebrum clears it from the notes of the related cells, so your notes stay current.
How do mistakes work in Sudoku?
The grid checks each digit as soon as you place it. A wrong digit counts as a mistake, and the third mistake ends the game, with a second chance on offer.
What does the Hint button do?
It walks you through the reasoning one step at a time and names the technique at work. It usually ends by revealing the digit; with a few advanced techniques it removes the impossible candidates from your notes instead.
Are there Sudoku variants in Cerebrum?
No. Cerebrum offers the classic 9×9 grid with no variants, from Easy to Elite.
Other games in Cerebrum
Minesweeper
iPhone · iPad · Android
Crossword
iPhone · iPad · Android
Word Search
iPhone · iPad · Android
Maze
iPhone · iPad · Android
Get Cerebrum
Free to download, with a banner during play and ads between some games. Rewarded ads are always optional. Premium, weekly, monthly or yearly and bought in each store, means no forced ads, plus extra perks. What Premium adds
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