Suguru is a free online number logic puzzle, also known as Number Blocks or Tectonic. The grid is cut into blocks of one to five squares. A block of two squares holds 1 and 2, a block of five holds 1, 2, 3, 4 and 5, each exactly once, and the one rule that ties the blocks together is that two equal numbers may never touch — not side by side, not above and below, and not diagonally at a corner. A handful of numbers are given; every other square follows from them. Tap a square and type or tap a number to write it in, switch on Notes to pencil in the numbers a square could still be, and anything that breaks a rule turns red at once. Writing a number also rubs it out of the notes around it, so the board keeps up with you. Every grid is built by the game itself rather than copied from a book — each level opens on its own grid, and New Puzzle deals another — and every one has exactly one answer and is proved solvable without guessing before you see it. Eight levels grow from a 5×5 to a 10×10, and from level 6 each grid needs at least one "what if" followed through to a contradiction. No download, no account.
How to play Suguru
- The grid is divided into blocks by thick lines. A block has one to five squares.
- Fill every block with the numbers 1 up to its size, each once: a 3-square block holds 1, 2 and 3.
- Two equal numbers may never touch — not across, not up and down, and not diagonally at a corner.
- Tap a square to select it, then tap a number on the pad or type 1 to 5. Numbers bigger than the selected square's block are greyed out.
- Tap the same number again, press 0, Backspace or Delete, or use the ⌫ key to rub a square out.
- Press Notes (or N) to pencil in small numbers instead; hold Shift while typing to pencil one in without switching. Writing a number in ink rubs it out of the notes in its block and in the eight squares around it.
- A number that breaks a rule turns red, and the line under the grid says how many squares are breaking one.
- On a keyboard, arrow keys move between squares.
- The grid is solved when every square is filled and no rule is broken.
- Undo steps back one change, Clear wipes your numbers and notes, and New Puzzle deals a different grid on the same level.
- The ? button writes one square of the answer, correcting a wrong number first. Three per grid.
Tips
- Start with the small blocks. A one-square block is always a 1, and a two-square block is 1 and 2 in some order — so the squares around it can often lose a 1 or a 2 at once.
- Look at the biggest number a block needs. In a five-square block, the 5 has to go somewhere, and only squares that do not touch another 5 can take it.
- When a number has only one square left in its block, write it in — even if that square could hold other numbers.
- A 1 in one block rules out 1 in all eight squares around it, and that often decides a neighbouring block's 1 straight away.
- Watch for shadows: if every place a block could put its 4 touches the same outside square, that square cannot be a 4, whichever place the block picks.
- Two squares of a block that can only be 1 or 2 between them take 1 and 2 away from the rest of that block.
- Pencil in notes on the bigger boards. Writing a number rubs it out of the notes around it, so the notes stay honest as you go.
- On the later levels, try a number in your head. If writing it leaves another square with nothing it can be, that number is wrong.
FAQ
Is Suguru free to play?
Yes. It runs in the browser with no download, no sign-up and nothing to buy. All eight levels are included and unlock as you solve them.
What are the rules of Suguru?
The grid is divided into blocks of one to five squares. Fill each block with the numbers from 1 up to the number of squares it has, each exactly once. Two squares holding the same number may never touch, including diagonally. That is all.
Is Suguru the same as Tectonic or Number Blocks?
Yes, it is the same puzzle under different names. It was invented in Japan by Naoki Inaba, and newspapers print it as Suguru, Number Blocks or Tectonic. The rules here are the classic ones, with nothing added.
Does every puzzle have exactly one answer?
Yes, and it is checked rather than assumed. Each grid is built from a real, complete answer, and givens are removed only while a program that makes forced moves alone can still finish it; a grid it can finish that way has only one answer. The tests confirm that with an exhaustive search on every level as well.
Will I ever have to guess?
No. A grid only ships if it can be finished by deduction alone. On levels 1 and 2 every move is direct — a square with one number left, or a number with one square left in its block. Levels 3 to 5 each need at least one shadow or pair: a square that every place a block could put a number would touch, or two squares of a block that share out two numbers between them. From level 6 on, each grid needs at least one "what if": try a number, follow it through, and see it break.
How many levels are there?
Eight, from a 5×5 grid to a 10×10. The grid grows, and the reasoning each level needs gets harder too: in testing over forty grids a level, the typical grid needed about two "what if" steps on level 6 and about five on level 8. New Puzzle deals a fresh grid on any level you have reached.
Why are there so few numbers given?
Because the blocks do much of the work. A two-square block is already half solved, and every number you write rules itself out of up to eight squares around it. The generator removes every given it can while the grid stays solvable by logic, so a 10×10 usually starts with about ten numbers.
Does it work on a phone?
Yes. Tap a square and tap a number on the pad under the grid. On a phone held upright the game uses a taller frame, so even the 10×10 grid keeps squares large enough to tap accurately.