How to Play Sudoku

Welcome to Sudoku at FunFunGames.com! If you’ve never played before (or just want a quick refresher), you’re in the right place.

This is the quick-start guide — enough to solve your first board without a headache. Prefer examples and visuals? Try the Walkthrough.

Want to learn advanced tips and all the game’s features? See General Sudoku Help.

The Goal

Fill every row, column, and bold 3×3 box with the numbers 1 to 9. The catch: each number can only appear once per row, column, and box!

What’s a “given number”?

Given numbers are the starting clues printed on the board when the puzzle begins. They never change. Everything else you type are your numbers. On our boards:

  • Given numbers appear in bold on a lightly tinted tile.
  • Your numbers that you can change appear on the other tiles.
5
3
7
6
1
9
5
9
8
6
8
6
3
4
8
3
1
7
2
6
6
2
8
4
1
9
5
8
7

Start with the obvious

Scan for spots that are almost finished. If a row already has eight different numbers, the last square is forced.

5
3
6
7
8
9
1
2
6
1
9
5
9
8
6
8
6
3
4
8
3
1
7
2
6
6
2
8
4
1
9
5
8
7
Row 1 is nearly full—what number is missing?

Use the 3×3 box

Every 3×3 box also needs 1–9 once. Cross-check rows and columns that pass through a box—often a number can only fit in one square.

5
3
4
7
6
2
1
9
5
1
9
8
6
8
6
3
4
8
3
1
7
2
6
6
2
8
4
1
9
5
8
7
9
Try placing the missing number in the top-left box.

Column check (same idea, vertical)

Columns work like rows: if a column is almost full, the remaining square is determined by what’s already there.

5
3
7
1
6
1
9
5
4
9
8
6
8
6
2
3
4
8
3
1
7
2
5
6
6
2
8
4
1
9
3
5
8
7
Which number can still go in that column?

Almost done

Near the end you’ll see a few squares that have only one legal option. Place those and the board will finish itself.

5
3
4
6
7
8
9
1
2
6
7
2
1
9
5
3
4
8
1
9
8
3
4
2
5
6
7
8
5
9
7
6
1
4
2
3
4
2
6
8
5
3
7
9
1
7
1
3
9
2
4
8
5
6
9
6
1
5
3
7
2
8
4
2
8
7
4
1
9
6
3
5
3
4
5
2
8
6
1
7
One square left—can you spot it?

FFG Difficulty Levels

  • Easy: smooth starts and frequent singles.
  • Medium: stronger cross-checking and candidate cleanup.
  • Hard: more advanced elimination patterns.
  • Expert: deeper chains and tougher endgames.
  • Legendary: maximum pressure, minimal freebies.

Technique Names You May Hear

  • Naked Single: only one value can go in a square.
  • Hidden Single: a number has only one possible spot in a unit.
  • Locked Candidate: a box can force eliminations in a row/column.
  • Naked Pair: two cells share the same two candidates, so peers lose those candidates.
  • Hidden Pair / Naked Triple: grouped candidates that eliminate extra options in a unit.
  • X-Wing: a cross-row/column pattern that removes one repeating candidate.
  • Guess / Backtracking: mostly in the top difficulty levels.

Quick Tips for New Players

  • Start with rows, columns, or boxes that are almost filled in.
  • Use logic and process of elimination first; save guessing for true dead-ends.
  • Don’t be afraid to erase or try again. Mistakes are part of the puzzle!
  • Try using Pencil Mode in our game to jot down possible numbers.

That’s it! You’re ready to try a puzzle or check out our most popular boards.

Want to learn advanced tips and all the game’s features? See General Sudoku Help.

Want to get fancy? We’ll have an advanced strategy page coming soon!