What is Hyper Sudoku?
Hyper Sudoku is normal sudoku with four extra mini-boxes added inside the grid. The board is the same 9×9 you already know, with the same 3×3 boxes, the same rows and the same columns. But there are four NEW 3×3 regions tucked inside the grid — and each of those four extra boxes also has to contain the numbers 1 to 9 with no repeats.
The four extra boxes sit one square in from each corner of the puzzle. We tint them a friendly mint green so you can see them at a glance. They stay the same colour while you click around the board — that’s on purpose, so the extra regions never disappear while you’re solving. If you’re already comfortable with our classic 9×9 sudoku, you already know most of the rules. Hyper Sudoku just adds the four extra mini-boxes on top.
Some puzzle books call this same game "NRC Sudoku" or "Windoku" or "4-square sudoku". The names are different, but the rules and the layout are exactly the same. Whatever a grown-up calls it, you’ve already played it!
How is Hyper Sudoku different from regular sudoku?
In a normal sudoku you have three rules: every row, every column and every 3×3 box must contain the digits 1–9 with no repeats. Hyper Sudoku keeps all three of those rules and adds a fourth one — the four extra mini-boxes (the tinted regions) must ALSO each contain 1–9 with no repeats.
Each extra mini-box is treated just like a normal 3×3 box: you can never put the same number twice inside it. If you’re about to place a 7 in one of the tinted regions and there’s already a 7 somewhere in that region, that move is blocked — even if the row, column and 3×3 box all look fine.
- 🟪 Every row, column and 3×3 box must contain 1–9 (same as classic sudoku)
- 🟢 Each of the four mint-green hyper boxes must also contain 1–9 with no repeats
- 🎨 The hyper boxes are tinted so you can see them without counting cells
- 🎯 The extra rules give you extra clues — solving can actually feel FASTER
The 4 simple rules
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One of each in every row
Every row needs the digits 1 through 9 — no repeats.
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One of each in every column
Every column needs the digits 1 through 9 — no repeats.
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One of each in every regular 3×3 box
Each of the nine standard 3×3 boxes needs the digits 1 through 9 — no repeats.
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One of each in every hyper box
Each of the four tinted hyper boxes (the mini 3×3 regions inset from the corners) must also contain the digits 1 through 9 — no repeats.
The hyper-box trick that unlocks the puzzle
The biggest shift going from classic sudoku to Hyper Sudoku is learning to "see" the four hyper boxes as real regions, not just decoration. Any time you’re about to place a digit inside one of the tinted regions, you have to check four things instead of three: the row, the column, the regular 3×3 box AND the hyper box.
That sounds like more work, but in practice it’s a huge gift. Cells that sit inside one of the hyper boxes are constrained by FOUR different lines at once. That’s a lot of clues for a single cell, so cells inside the hyper regions are usually the easiest cells on any Hyper Sudoku.
A great way to start every puzzle is to look at the four hyper boxes first. Count the digits already in each one — if a hyper box has six or seven of the nine digits, the rest are almost solved already.
Easy strategies for kids
- ✨ Solve cells inside the hyper boxes first — they have more clues pointing at them
- 📐 Scan all four hyper boxes before every move
- 🔢 Use the 45-sum trick on a nearly-full hyper box
- ✏️ Tap Notes to pencil in possible candidates
- 💡 Auto Notes takes the hyper boxes into account for you
Most kids pick up Hyper Sudoku in about five puzzles. If you’ve never played sudoku of any kind, a couple of rounds at Easy 9×9 sudoku first will get the basic pattern into your head. Once rows, columns and boxes feel automatic, the hyper regions are a fun extra layer on top.
Why kids love Hyper Sudoku
- 🧠 Trains visual thinking — spotting patterns inside small regions
- 🎨 The mint-green hyper boxes make every puzzle look lovely and clear
- 🕵️ Detective brain — the extra rules give you extra clues
- ⏱️ Quick wins on Easy, longer challenges on Expert
- 📱 Plays great on phones, tablets, Chromebooks and laptops
Ready for more?
Once Easy Hyper Sudoku feels comfortable, try Medium Hyper Sudoku. From there you can graduate to Hard Hyper Sudoku, and finally take on Expert Hyper Sudoku — our toughest hyper puzzle.
Want a totally different brain workout? Try our X-Sudoku (sudoku with two big diagonals), our Killer Sudoku (sudoku with cage sums) or our Jigsaw Sudoku (classic rules, but the boxes are wiggly shapes). Younger players can also try our 4×4 sudoku and 6×6 sudoku starter grids.
Frequently asked questions
What age is Hyper Sudoku good for?
Most kids enjoy Hyper Sudoku from about 8 years old, once they’re comfortable with regular sudoku. Younger kids should start with our 4×4 or 6×6 starter grids, then move to classic 9×9, and add the hyper rule when rows, columns and boxes feel automatic.
Is Hyper Sudoku harder than normal sudoku?
Not always! The four extra mini-boxes add more constraints, but they also give you more clues. On Easy and Medium, most kids find Hyper Sudoku about the same difficulty as regular sudoku — sometimes even a bit quicker, because cells inside the hyper boxes have four lines pointing at them.
Why is it called Hyper Sudoku?
The name comes from the idea of "hyper" rules — extra rules on top of regular sudoku. Some puzzle books call the same game NRC Sudoku, Windoku or 4-square sudoku, but the rules are identical.
Where exactly are the four hyper boxes?
Each of the four hyper boxes is a 3×3 region inset by one cell from the corners of the grid. So the top-left hyper box covers rows 2–4 and columns 2–4 (counting from 1). Same idea for the other three corners. We tint them mint green so you can always see them.
Is Hyper Sudoku the same as Windoku?
Yes! Hyper Sudoku, NRC Sudoku, Windoku and "4-box sudoku" are all the same puzzle — classic sudoku plus four extra 3×3 regions inside the grid. Different sites use different names.
Can I play without making an account?
Yes! Every game on this site is free, with no signup, no email, and no ads in the way of the puzzle.
Does it save my progress?
Yes — your puzzle, notes and timer save automatically in your browser. Close the tab and come back later, it’ll still be there.
Try other sudoku games
Different rules, same friendly board. Pick a sibling puzzle to play next.