Suguru vs sudoku
If you play sudoku, you're most of the way to playing Suguru. Both are grids of numbers with no maths in them, both have exactly one answer, and a lot of the thinking carries over. They still feel quite different to solve, and the reasons are worth knowing.
Side by side
| Rule | Sudoku | Suguru |
|---|---|---|
| Grid | Always 9×9 | Any size. Here, 5×5 to 8×8 |
| Numbers | 1 to 9 | 1 up to the size of the block, so rarely above 5 |
| Areas | Nine 3×3 boxes | Blocks of every shape, usually 1 to 5 cells |
| Rows and columns | 1 to 9, once each | No rule at all |
| Repeats | Never in the same row, column or box | Never touching, not even at a corner |
| Also called | Number Place | Tectonic, Number Blocks |
How far a number reaches
This is the difference you feel most. In sudoku, a 5 rules itself out of its whole row, its whole column and its box: 20 cells, some of them on the far side of the grid. In Suguru a number only reaches the cells touching it and the rest of its own block. That's 8 cells here, and never more than 11.
Sudoku
Suguru
So the two puzzles ask you to look in different ways. Sudoku is about long lines: you scan a row, a column, a box. Suguru is local. You look at a cell and the ring around it, or at a block and whatever is pressing on it from outside. If you've played Minesweeper, that kind of looking will feel familiar.
In Suguru, the numbers mean something
In sudoku the digits are just labels. Swap them for letters or colours and the puzzle doesn't change. In Suguru the size of a number matters, because a block can't hold anything bigger than its size. A 5 can only go in a block of 5. Every block needs a 1, though, so small numbers are everywhere and big ones are scarce.
It also means the shape of the grid carries information before you've read a single clue. Any 2×2 square needs four different numbers, since every cell in it touches the other three, so the blocks meeting there have to be big enough to supply them. When I wrote the puzzle generator, that one fact ruled out about half of the random 8×8 layouts it tried.
What carries over from sudoku
More than you'd expect. The basic moves have the same names and work the same way:
- the only number a cell can be (a naked single)
- the only place a number can go (a hidden single)
- pairs and triples, naked and hidden
If you can do those in sudoku, you can do them here. The one habit to add is checking diagonals, every time. The solving techniques guide has each one drawn out on a Suguru board.
What doesn't
Anything built on rows and columns. There's no X-wing or swordfish in Suguru, because there are no lines for them to run along. In their place you get tricks that run on the touching rule, like a cell losing a number because it touches every spot that number could go.
Which is harder?
Neither, really. Both go from gentle to properly tough. What's different is the size. A Suguru grid is smaller, so even a hard one is usually over sooner than a hard sudoku, and it fits on a phone screen without squinting. That's a big part of why I picked Suguru for a daily puzzle.
If you already play sudoku, Monday's 5×5 will take you a few minutes while you get used to the corners. By Wednesday you'll be using the same tricks you use in sudoku.
Where Suguru comes from
Suguru was invented in Japan by the puzzle designer Naoki Inaba. It's also published as Tectonic (or Tectonics) and Number Blocks, depending on where you find it. If you've done a Tectonic puzzle in a magazine, it's this one.
Sudoku had another name at the start, too. It first appeared in an American puzzle magazine in the late 1970s as Number Place, and only picked up the Japanese name later.
More guides
- Suguru for beginners
The two rules, the mistake nearly everyone makes at first, and a small puzzle solved one step at a time. - Suguru solving techniques
Six ways to make progress, from the only number left to a short what-if, each with a worked example.