🧱 Suguru Puzzles

Suguru: The Puzzle Where Numbers Aren't Allowed to Touch

Most number puzzles ask you to look along a line. Sudoku wants you to scan a whole row. Kakuro wants you to add up a run. Suguru asks you to do something different, and once it clicks it's oddly addictive: it asks you to look at the eight cells around the one you're staring at.

That's the whole trick. Every number you write down puts a little invisible fence around itself, and nothing identical is allowed inside that fence. Get comfortable with that idea and you can solve these all day.

📏 The Two Rules (That's Genuinely All of Them)

The grid is chopped up into outlined blocks of different shapes and sizes. Then:

1. Each block holds 1 up to however many cells it has. A five-cell block holds 1, 2, 3, 4 and 5 — one of each. A three-cell block holds 1, 2 and 3. A lonely one-cell block holds a 1, and that's that.
2. Identical numbers may never touch. Not side by side, not above or below, and — this is the one that catches everybody — not diagonally either.

Notice what isn't in that list: there is no row rule and no column rule. A row in Suguru can contain three 2s quite legally, as long as none of them are neighbours. Players arriving from Sudoku often spend their first puzzle scanning rows out of pure habit and getting nowhere. Let that reflex go.

👀 What "Not Even Diagonally" Actually Looks Like

Here's a 3 sitting in the middle of a grid. Every cell marked ✕ is now banned from being a 3:

Eight cells is a lot of influence for one little digit. It's also why Suguru grids can be solved from surprisingly few clues: a single given number reaches into every block that touches it.

🪜 Your Opening Three Moves

Every Suguru has a soft spot. Here's the order we use when starting a fresh grid:

1. Find the smallest blocks. A three-cell block only ever holds 1, 2 and 3 — three unknowns instead of five, and a much shorter list to work through. Small blocks are where certainty lives.
2. Look at the cells where blocks bump into each other. A cell wedged against three different blocks is being squeezed from every direction. Those are the cells that crack first.
3. Chase the givens. Take each number already printed on the grid and mentally cross out that number in all eight cells around it. Do this for every given before you write anything. Half the puzzle usually solves itself from this pass alone.

🧠 Six Techniques That Actually Crack Suguru

These are the moves we lean on, roughly in the order you'll need them.

1. The lonely number. Point at an empty cell and list what it could still be: start from 1 up to its block's size, cross off anything the block already has, then cross off anything sitting in the eight cells around it. If one number survives, that's the answer. This is the workhorse — most cells on an Easy grid fall to it.

2. The lonely cell. The same question asked from the other direction. Take a block, and for each number it still needs, ask "how many cells could hold this?" If the answer is one, write it in. Techniques 1 and 2 together are enough to finish every Easy and Medium puzzle on this page.

3. The squeeze from next door. This is the one that unlocks our Hard puzzles, and it's worth learning properly. You don't need to know where a number goes to use it. Suppose a block still needs a 3, and you've narrowed it down to two possible cells. Now look for any cell that touches both of those candidates. Wherever that 3 finally lands, it will end up next to that cell — so that cell cannot be a 3, and you can rule it out right now. Two maybes, one certainty.

4. Pairs inside a block. If two cells in a five-cell block can only be 2 or 5, then 2 and 5 are used up — the other three cells must be 1, 3 and 4. It's the same idea as a naked pair in Sudoku, but confined to the block, so it's much easier to spot.

5. The 1 problem. Every single block on the grid contains a 1 — even the tiny ones. That makes 1 by far the most common number on the board, which means the "can't touch" rule bites hardest for 1s. When you're stuck, try mapping out where the 1s can't go. They're usually forced into surprisingly few places.

6. Big numbers are rare. A 5 can only exist inside a five-cell block. If your grid only has a handful of those, then 5s are scarce, spread out, and easy to pin down. Whenever a puzzle feels impenetrable, count how many blocks are large enough to hold its biggest number — the answer is often "not many."

🚧 Three Mistakes Almost Everyone Makes

• Forgetting the diagonals. The classic. You place a 2, it looks perfectly fine, and there's another 2 sitting corner-to-corner in the block next door. Our grid turns clashing numbers red the moment you place them, so you'll catch it — but train yourself to check the corners before you commit.
• Importing the row rule from Sudoku. Two 4s in the same row are absolutely fine in Suguru. If you find yourself rejecting a correct answer, check whether you're enforcing a rule that doesn't exist here.
• Ignoring the block shape. Suguru blocks are irregular on purpose. An L-shaped block folds around a corner, so cells in it can be diagonal neighbours of each other — meaning that block's own numbers constrain themselves twice over. Snake-shaped blocks are the friendliest; compact square blocks are the tightest.

🎚️ Grid Sizes and Levels on This Page

Four sizes, and they play quite differently:

• 5 × 5 — about five blocks. Solvable in a couple of minutes and perfect for learning the diagonal rule without getting overwhelmed.
• 6 × 6 — our default. Enough room for genuinely interesting block shapes, still finishable over a cup of tea.
• 7 × 7 — the sweet spot for regular players. Long chains of reasoning start appearing.
• 8 × 8 — thirteen or so blocks and plenty of space to get lost in. Set aside a bit of time.

The three levels aren't just "fewer numbers to start with" — they change which techniques you'll need:

• Easy 😊 — solvable start to finish on techniques 1 and 2 above, and we deliberately leave extra clues on the grid so you're never hunting for long. Good for learning the diagonal rule.
• Medium 🤔 — the same two techniques, but we strip the grid back as far as those techniques will carry it. Every move is still a "this is the only cell / only number" step; you just have to look harder to find it.
• Hard 🧠 — these need the squeeze from next door (technique 3). At some point the singles dry up completely, and the only way forward is to rule a number out of a cell without knowing where that number actually goes.

🎮 Playing on This Page

• Click or tap a cell and a small keypad appears, showing only the numbers that block can actually take — a three-cell block offers you 1, 2 and 3, nothing more.
• Use your keyboard if you prefer: arrow keys to move, a number key to place, Backspace or Delete to clear.
• On a phone, the number strip above the grid works with whichever cell you've selected.
• Clashes turn red. Two identical numbers touching, or a repeat inside a block, will both light up straight away.
• Hint 💡 fills in one correct cell and flashes it orange, so you can see where the logic was hiding.
• Solution ✅ reveals the finished grid — handy for working backwards to understand a block that beat you.

🌏 Where Suguru Came From

Suguru is the work of Naoki Inaba, a Japanese puzzle designer with an enormous back catalogue of original grid puzzles. It travelled quickly and picked up new names along the way: in the Netherlands and Belgium it's sold as Tectonic, British newspapers and puzzle magazines often print it as Number Blocks, and you'll occasionally see the Japanese Nanbaburokku. Same two rules underneath, every time.

Part of the reason it spread so well is that it needs almost no explanation. You can hand a Suguru to someone who has never done a logic puzzle, say "each block gets 1 up to its size, and matching numbers can't touch," and they can start immediately. Very few puzzles clear that bar.

🧒 Why It's a Brilliant Puzzle for Younger Players

We test these on children as well as adults, and Suguru consistently lands well — here's why:

• No arithmetic. Nothing is added, multiplied or divided. The numbers are really just five distinguishable symbols, so a child who finds sums stressful can still be excellent at this.
• The counting is tiny. "This block has four cells, so it needs 1, 2, 3 and 4" is well within reach of a six-year-old.
• Mistakes are visible. A clash turns red immediately, so the puzzle teaches rather than punishes.
• It builds spatial habits. Checking eight surrounding cells before committing is genuinely useful thinking — the same scan chess players and Minesweeper players learn.
• Small grids finish fast. A 5 × 5 gives you the satisfaction of a completed puzzle in a few minutes, which matters a lot when you're building the habit.

🚀 Give It a Go

Scroll back up, leave it on 6 × 6 Medium for your first one, and start with the smallest block you can find. Cross out mentally, place what's forced, then move next door. Once the diagonal rule stops feeling like a trap and starts feeling like a tool, you'll wonder why you ever needed rows and columns. 🧱