Happy Life GamesHow to Play Sudoku: Rules, Solving Steps and Tips for Beginners
Sudoku asks one thing of you: fill the grid so that no number repeats in any row, column or box. No arithmetic is involved. What makes it satisfying is that every puzzle can be cracked by reasoning alone. Each cell you fill is a small proof, and each proof makes the next one easier, until the last few numbers fall into place almost by themselves.
Our version, Sudoku Easy, starts on tiny 4x4 grids so you can learn the logic without drowning in digits, then moves up to 6x6 and finally the classic 9x9. This guide covers the rules, the exact techniques the game teaches, and what to do when the grid goes quiet.
Rules and controls
The grid is divided into rows, columns and boxes (the blocks with thick outlines). A 4x4 grid has four 2x2 boxes and uses the numbers 1 to 4. A 6x6 grid has six boxes that are two rows tall and three columns wide, and uses 1 to 6. A 9x9 grid has nine 3x3 boxes and uses 1 to 9. When the puzzle is finished, every row, every column and every box contains each number exactly once.
- Tap an empty cell to select it. After each correct entry, the selection jumps to the next empty cell for you.
- Tap a number on the keypad below the grid to place it.
- A correct number locks in. A wrong one makes the board shake, and the number is not placed.
The counter at the top shows how many cells are left to go. Completed rows, columns and boxes light up with a quick sweep. Fill the last empty cell and the level is solved.
From level 11 onward you also have three hearts. Each wrong number costs one, and losing all three ends the attempt. That rule is fair because every puzzle here can be solved without guessing, and the game reminds you of exactly that after a couple of wrong entries.
Under the board, a short line names the idea the level is built around, such as "Only spot in a box." A few cells also carry stars. Those are the cells where that idea is actually needed, so they make good targets when you are not sure where to look.
Beginner strategy: three moves to master first
1. Fill the last gap
Look for any row, column or box with exactly one empty cell. The missing number is simply whichever one is not there yet. On 4x4 grids this move alone carries you through most of the puzzle, and on 9x9 grids you will use it constantly near the end.
2. Only spot in a box
Pick a number, say 3, and a box that does not contain a 3 yet. Now find every 3 already on the board. Each one rules out its entire row and column. Imagine those lines crossing through your chosen box. If only one empty cell in the box survives, that is where the 3 goes. Solvers call this cross-hatching, and level 3 is where the game introduces it.
3. Go number by number
Rather than staring at random cells, work through the digits one at a time. Start with the number that already appears most often on the board. It has the fewest places left, so its remaining copies are the easiest to pin down. Place every copy you can prove, then move on to the next most common digit.
Advanced techniques
Once you reach the 9x9 boards, puzzles begin to require specific techniques. Each one arrives with a "NEW" banner, and the hint button names the technique whenever it uses one.
Only spot in a line (level 26)
This is cross-hatching applied to a row or column instead of a box. Take a row that is missing a 7. For each empty cell in that row, check whether its column or its box already holds a 7. If every empty cell but one is blocked, the 7 has only one possible home. Lines are harder to scan than boxes, so trace them slowly.
Only number that fits (level 35)
Here you flip the question. Instead of asking where a number can go, ask which number can go in a particular cell. Choose a cell that sits in a crowded row, a crowded column and a crowded box. Collect every digit that appears anywhere across those three groups. If eight of the nine digits are already taken, the ninth is the answer. The hint message for this move reads "Only N fits: row+column+box."
Pairs point the way (level 80)
Sometimes no single cell can be decided directly, and you need one extra step of reasoning. Suppose that inside one box, the number 5 can only go in two cells, and both of those cells sit in the same row. You do not know yet which of the two gets the 5, but you do know that the 5 for that whole row must be inside this box. So you can rule out 5 from every other cell in that row outside the box. That elimination usually unlocks an easy placement somewhere else. It also works the other way around: if all of a row's possible spots for a digit fall inside a single box, that digit cannot go anywhere else in the box. This idea is known as locked candidates.
Common mistakes
- Guessing to save time. On hearts levels, a guess can cost you a heart, and even a lucky guess teaches you nothing about why it worked. If you cannot prove a number, move to another part of the grid.
- Misreading the 6x6 boxes. These boxes are wider than they are tall, so it is easy to put a cell in the wrong one. Check the thick outlines before you rely on a box.
- Only scanning boxes. Box checks feel the most natural, but later puzzles are built so that the key move is in a row or column. When boxes give you nothing, switch to lines.
- Tunnel vision. A stuck corner usually needs a number from elsewhere first. Step back and look for the easiest move anywhere on the board.
What changes in later levels
Levels 1 to 5 are 4x4 grids, levels 6 to 20 are 6x6, and from level 21 on every puzzle is a full 9x9. Hearts arrive at level 11. After that, difficulty climbs in a sawtooth pattern: every tenth level is a tougher puzzle with more empty cells and the hardest technique of that stage, and the level right after it is a lighter breather. Later 9x9 puzzles also leave fewer cells that can be decided at the very start, so spotting your first move becomes part of the challenge.
FAQ
Do I ever need to guess?
No. Every puzzle is built so it can be solved with the techniques above, which also means it has exactly one solution. If guessing feels necessary, there is a logical move you have not found yet.
What does the hint button do?
It finds the next cell a person could deduce right now, fills it in, highlights the row, column or box that proves it, and shows a short reason such as "Last empty cell in this row." Reading that reason is a quick way to learn each technique.
Can I write pencil marks?
There is no notes mode, so candidates live in your head. On 9x9, focus on a single number or a single cell at a time instead of trying to track everything at once.
What happens when I run out of hearts?
The attempt ends and you can start the level again. If a level keeps beating you, the skip button moves you on to the next one.