sudoku for beginners: rules and solving tips

Sudoku rules in one minute

A Sudoku grid has nine rows, nine columns, and nine 3 × 3 boxes. Fill every empty cell with a number from 1 to 9 so that each number appears once in every row, column, and box.

You do not need arithmetic. The numbers are symbols, and the puzzle is solved by elimination. Every puzzle generated by Playfun Sudoku is checked to have one solution.

Choose the right difficulty

Playfun begins on Medium, but Easy is the better place to learn the interface and the core patterns.

• Easy keeps 42 starting clues.
• Medium keeps 34 starting clues.
• Hard keeps 28 starting clues.

Fewer clues usually require more candidate tracking and longer chains of deduction. Difficulty changes the number of clues, not the basic rules.

How the Playfun controls work

Select an empty square, then tap a number from 1 to 9. On a keyboard, you can select squares with the arrow keys and enter a digit directly. Backspace, Delete, or 0 erases an entry.

Turn Notes on to add small candidate numbers without committing to an answer. Tap the same candidate again to remove it. Given clues cannot be edited.

Playfun marks an incorrect committed answer and adds it to the mistakes counter. There is no three-strike ending, so the counter is feedback rather than a life limit. For a more traditional logic challenge, use notes and place a full-size number only when you can explain why it must fit.

Step 1: scan for missing numbers

Start with a row, column, or box that already contains many clues. List which numbers from 1 to 9 are missing. For each empty square, rule out numbers already present in that square's row, column, and box.

If only one number can fit a square, you have a naked single. Place it, then scan the connected row, column, and box again. One single often creates another.

Step 2: look for hidden singles

Sometimes a square has several candidates, but one candidate can appear nowhere else in its row, column, or box. That candidate is a hidden single.

For example, suppose a 3 × 3 box needs 2, 5, and 8. Two empty cells are blocked from holding 8 by their columns. The remaining cell must be 8 even if it also appears to allow 2 or 5.

Hidden singles are easier to see when you scan one number at a time. Pick a number, such as 7, and check where it can go in each box.

Step 3: maintain useful notes

Notes should make the grid easier to read. Add candidates to cells in the area you are actively solving instead of filling every empty square immediately.

After placing a number, remove that candidate from peers in the same row, column, and box. Playfun does not automatically clean up your notes, so keeping them current is part of the solve.

If two cells in one unit contain the same exact pair of candidates, those two numbers are reserved for those cells. Other cells in that row, column, or box cannot use the pair. This naked pair is a helpful next step when singles run out.

Step 4: use box-line interactions

Look inside one 3 × 3 box. If every possible location for a candidate lies on the same row, that number cannot appear elsewhere on that row outside the box. The same idea works with columns.

This technique is often enough to turn a Medium puzzle back into a sequence of singles. After eliminating candidates, rescan the whole grid rather than staying fixed on one difficult corner.

What to do when stuck

Use this short reset routine:

1. Check every nearly complete row.
2. Check every nearly complete column.
3. Scan each box for one number at a time.
4. Update notes around your most recent placements.
5. Look for pairs before considering a guess.

If the board still seems impossible, inspect earlier entries—especially any red number. A single incorrect commitment can make several later cells appear contradictory.

Quick answers

Does the timer affect the puzzle?

No. It records elapsed seconds for your result but does not change the rules or end the game.

Can I make notes with the keyboard?

Turn Notes on with the on-screen button, then press number keys. The selected cell receives or removes small candidates.

Should beginners guess?

No. Playfun's puzzles have a unique solution, and Easy puzzles are designed to yield to scanning and elimination. Guessing makes it harder to learn why an answer is correct.

Start an Easy Sudoku or find another free puzzle game.