Suguru: rules, tips and free puzzles online

Suguru is a grid split into small outlined regions. A region of k cells holds the digits 1 to k once each, and two cells that touch, even at a corner, never hold the same digit. Play suguru online free here, on grids from 5×5 to 8×8.

The puzzle is also sold as Tectonic, Number Blocks or Nanbaburokku. There are no rows or columns to fill, so the logic feels quite different from sudoku: everything happens between neighbours.

The rules

• The grid is divided into regions of one to five cells. A region with k cells contains each digit from 1 to k exactly once.
• Two cells that share an edge or a corner never contain the same digit, even if they are in different regions.
• Digits already in the grid are given clues.

How to start

One-cell regions

A region of one cell can only hold 1. That 1 then rules 1 out of all eight cells around it, which often settles the regions next door.

Count what a region still needs

Every region of size k needs all of 1 to k. List the digits a region is missing and ask where each one can go. If a 3 can only fit in one cell, it goes there, even when that cell has other candidates too.

Shared neighbours

If every cell where a region could put its 2 touches the same outside cell, that outside cell can’t be 2. This is the suguru version of pointing, and it is the main tool on the harder ranks. Pairs and triples work too, within a region. See our solving techniques guide for how they work in general.

Common mistakes

• Forgetting the diagonal neighbours. Cells that only touch at a corner still can’t match.
• Putting a digit bigger than the region’s size in it. A three-cell region never holds a 4.
• Checking only within a region. The touching rule crosses region borders.

How the ranks scale difficulty

The same four ranks apply here as everywhere on the site. Lemma is a gentle warm-up, Proposition needs a real idea or two, Theorem is near-minimal with almost every clue load-bearing, and Conjecture is the sparsest of all, so expect to think hard.

Suguru grids run from 5×5 at Lemma to 8×8 at Conjecture, with fewer given digits at each rank. Regions are up to five cells.

There are 99,999 puzzles per rank, each with its own number, so you can replay one or share it. Every type also has a 30-puzzle collection that climbs from Lemma to Conjecture. Every puzzle is checked to have exactly one solution that you can reach by logic alone, with no guessing.

Keep exploring

• FutoshikiA Latin square with < and > signs between neighbouring cells.
• KakuroA numerical crossword: runs of distinct digits 1–9 that hit their sums.
• Anti-Knight SudokuNo digit repeats a chess knight’s move away.
• Solving techniquesSingles, pairs, cage arithmetic, line logic and Latin squares, all in one guide.
• All puzzle guidesEvery puzzle type on Hoot’s Puzzles, with rules and tips.