How to Play Sudoku for Beginners
Sudoku has one rule. Fill a 9x9 grid so that every row, every column, and every 3x3 box contains the numbers 1 through 9 exactly once. That's the whole game. What makes it hard isn't the rule - it's figuring out which number goes where without guessing.
Most beginners quit in the first week because they treat Sudoku like a guessing game. It isn't. Every legitimate puzzle can be solved through logic alone, and once you learn two techniques, you'll clear easy and medium puzzles without much trouble.
Start with the obvious cells
Before doing anything clever, scan the grid for rows, columns, or 3x3 boxes that are almost full. If a row already has seven of nine numbers placed, the two empty cells only have a couple of possible values between them. These near-complete lines are where every Sudoku puzzle actually starts, not the empty-looking corners.
Crosshatching: the first real technique
Pick a number, say 5, and pick a 3x3 box that doesn't have a 5 yet. Look at every row and column that passes through that box. If a row already has a 5 somewhere else, no cell in that row - inside the box you're checking - can hold a 5. Do the same for columns. Cross out the impossible cells, and often only one is left. That's your 5.
Repeat this for each number, one box at a time. It's mechanical, which is exactly why it works when you're new - you don't need to spot subtle patterns yet, just eliminate what can't be true.
Scanning rows and columns
The companion technique to crosshatching is scanning: for a specific empty cell, look at everything already placed in its row, its column, and its box, and write down what's left. If a cell's row has 1, 2, 4, 6, 8 and its column has 3, 7, only 5 and 9 remain possible for that cell. Sometimes that narrows it to one answer immediately.
Use pencil marks - don't try to hold it all in your head
Write the candidate numbers small in the corner of each cell (or use the hint/note feature if you're playing digitally). Trying to track five candidate numbers per cell across an entire grid from memory is how good players make dumb mistakes. Pencil marks turn Sudoku from a memory test into a pattern-spotting exercise, which is the actual skill you're building.
The mistake that ruins beginners: guessing
When a puzzle gets tough, the instinct is to pick a plausible-looking number and see what happens. Don't. A single wrong guess early on cascades - every deduction you make afterward inherits that error, and you won't notice until the whole grid contradicts itself twenty minutes later. If you're stuck, that's a sign you haven't found the right cell to focus on yet, not a sign to gamble. Step back, re-scan, or start a fresh puzzle if you're using pen and paper.
How long should a puzzle take?
An easy puzzle with crosshatching and scanning alone should take 5 to 15 minutes once you've had some practice. Medium puzzles that need pencil marks and a bit of pattern recognition run 15 to 30 minutes. If you're spending an hour on an "easy" puzzle, you're probably missing one of the two core techniques above rather than lacking some deeper skill.
Practice both techniques on a real grid: play free Sudoku on Mindhack.in, with auto-check turned on so you get instant feedback on whether a placement was actually correct instead of finding out ten moves later.
What to learn next
Once crosshatching and scanning feel automatic, the next step up is "naked pairs" - when two cells in the same row, column, or box can only hold the same two candidate numbers between them, which lets you eliminate those numbers from every other cell in that line. That's a hard-puzzle technique, though. Get comfortable with the basics first; they solve the vast majority of puzzles you'll actually run into.