Sudoku is one of the most popular puzzle games in the world — and despite all those numbers, it involves no math at all. If you've always wanted to learn, this complete guide covers everything: the rules, a worked example, beginner techniques, difficulty levels and answers to common questions. And good news — Sudoku is available now on Bardak.
What is Sudoku?
Sudoku is a logic puzzle played on a 9×9 grid, divided into nine smaller 3×3 boxes. Some numbers are filled in to start; your job is to complete the rest using logic alone. There's only ever one correct solution, and you can always reach it by reasoning — never by guessing.
Sudoku has no math
This trips up a lot of beginners: Sudoku uses the digits 1–9, but you never add, subtract or multiply anything. You could replace the numbers with nine colors, letters or shapes and the puzzle would work exactly the same. It's pure pattern logic.
The one rule you need to know
Fill the grid so that:
- Every row contains the numbers 1 to 9, with no repeats.
- Every column contains the numbers 1 to 9, with no repeats.
- Every 3×3 box contains the numbers 1 to 9, with no repeats.
That's the entire game — place each number 1–9 exactly once in every row, column and box.
What you need to play
Just the puzzle. In Bardak, Sudoku is built in: pick a difficulty and a fresh puzzle appears, with helpful tools like pencil marks and mistake-checking. You can play solo, offline, anytime — no pen, no paper, no setup.
How to start solving (step by step)
1. Scan for easy wins. Look at rows, columns and boxes that are almost full — often only one number can go in the empty cell. 2. Use "the only place" logic. Pick a number, say 7, and check a box: if there's only one cell where a 7 can legally fit, place it. 3. Pencil in candidates. For trickier cells, note every number that's still possible. As you place numbers elsewhere, cross candidates off. 4. Work box by box. Focus on one 3×3 box and figure out what's missing, then move on.
A worked example
Imagine a row that already contains 1, 2, 3, 4, 5, 6, 7, 9 and one empty cell. Only 8 is missing from that row, so the empty cell must be 8 — no other option is possible. That's the simplest kind of deduction, and easy puzzles are full of them. Harder puzzles just chain several of these together.
Beginner techniques that work
- Cross-hatching: for a single number, scan the rows and columns crossing a box to eliminate cells, leaving the one spot it must go.
- Naked singles: a cell where eight of the nine numbers already appear in its row, column or box — the ninth is forced.
- Pencil marks: keeping candidates tidy turns a confusing grid into a solvable one, especially on medium puzzles.
Difficulty levels explained
Sudoku puzzles are rated by how much logic they demand, not by the size of the grid:
- Easy: lots of starting numbers and simple deductions — perfect for learning.
- Medium: fewer givens; you'll need pencil marks and a bit of patience.
- Hard / Expert: advanced techniques and longer chains of logic.
In Bardak you can pick any level from easy to expert, so you can start gentle and work your way up.
Common beginner mistakes
- Guessing. Every valid Sudoku is solvable by logic — if you're guessing, look again; you'll find a move you missed.
- Ignoring pencil marks. On medium and hard puzzles, trying to hold everything in your head leads to errors.
- Tunnel vision. If a box is stuck, switch to a different row, column or box — progress there often unlocks the first one.
- Rushing. Sudoku rewards calm, careful scanning.
Why people love Sudoku
Sudoku is calming, satisfying, and genuinely good for your brain — it's a workout for logic, focus and patience, and one of the most relaxing ways to unwind on a commute, in a waiting room, or before bed. We go deeper in the benefits of playing Sudoku.
Frequently asked questions
Is Sudoku hard for beginners? No — start with easy puzzles. They have more given numbers and gentle logic. See easy Sudoku for beginners.
Do you need to be good at math? Not at all. Sudoku is pure logic; you never do arithmetic.
Is there always one solution? Yes. A proper Sudoku has exactly one solution, reachable by logic alone.
Is Sudoku free on Bardak? Yes — free, offline, with no ads and no in-app purchases.
Play Sudoku now on Bardak
Now that you know how to play Sudoku, the best way to improve is simply to play. Download Bardak free and solve your first puzzle today — puzzles from easy to expert, offline, with no ads.
Ready for more? Level up with Sudoku tips and tricks.