How to Play Sudoku — Rules & Strategy

How to play Sudoku

Start by scanning each 3×3 box for digits that can only go one place — if a row already holds a 7 and a column crossing the box holds a 7, the box's 7 is forced into the remaining cell. These 'singles' will carry you through every easy puzzle.

When scanning stalls, switch to pencil marks: note every candidate digit in each empty cell. Now look for naked pairs (two cells in a unit sharing the same two candidates — those digits can be erased everywhere else in the unit) and hidden singles (a digit with only one possible home in a unit, even if the cell has other candidates).

Harder puzzles add geometry: pointing pairs (a digit confined to one row inside a box eliminates it from that row outside the box), X-wings, and XY-wings. Each technique is just a repeatable elimination pattern — learn one at a time and hard puzzles stop being scary.

Mistakes are capped at three per puzzle. Burn through all three and you can spend 2 quarters to continue with your progress intact, or start fresh with a new free play.

Frequently asked questions

Are these sudoku puzzles free?

Yes — three free puzzles per difficulty per day, plus the free daily challenge. Quarters only buy extras: hints, auto-checking, and continues after three mistakes.

Does every puzzle have exactly one solution?

Yes. Every board is machine-verified to have a unique solution before it's served. If logic seems to run out, there is always a deduction available — that's what the hint button finds.

What's the difference between easy and expert sudoku?

The techniques required. Easy puzzles solve with simple scanning; expert puzzles require advanced elimination patterns like X-wings and chained inferences. Clue count alone doesn't determine difficulty.

Is sudoku good for your brain?

Sudoku exercises working memory, pattern recognition, and systematic reasoning. Research on puzzles suggests regular mental challenge supports cognitive engagement, though it isn't a medical treatment for anything — it's just genuinely good practice in careful thinking.

What is the daily sudoku?

Today's Odds is one identical puzzle served to every player in the world each day, free to attempt once. Finish it to log your time on the leaderboard and copy a spoiler-free result grid to share.

How do hints work?

A hint costs 1 quarter and reveals the next cell that is logically forced given the current board, along with which row, column, or box forces it — so you learn the technique instead of just getting an answer.