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Center Dot Sudoku Rules

A brief guide

This is an example of a completed Suguru puzzle. Suguru is played on a grid split up in to irregular shaped regions. The number of cells in each region will vary from one cell, up to six cells for the bigger puzzles.
The aim of Suguru is to fill each n-sized region with the numbers 1-n. For example, if a region has 3 cells, you need to insert the numbers 1, 2 and 3 in to those cells. If a region has 4 cells, you need to insert the numbers 1, 2, 3, and 4 in to those cells.
Each number can't be next to the same number in an adjacent cell, this includes horizontally, vertically, and diagonally.
This is an example of a starting Suguru grid - some cells have been filled in already, but most are empty.
I have highlighted three cells here that we can fill in to begin with,
  1. This puzzle has a region with just one cell (in the center), this cell must be a 1. Most puzzles don't have a region with just a single cell in this way, but this puzzle does!
  2. The cell on the left-hand side of the puzzle is in a region with 5 cells, so this region must contain a '5'. The '5' must be in the highlighted cell because the other two empty cells are next to the '5' on the bottom row.
  3. The highlighted cells towards the top is in a region with 5 cells, so this region must contain the numbers 1-5. The highlighted cell must be a '4'. All of the other cells are next to another '4', remember that diagonals count as well!
We are now up to this point. Both the highlighted cells must be a '1'.
The top-most highlighted cell is in a region with 5 cells, one is filled with a '4', and the other three cells that aren't highlighted are all next to the single '1' that we have just filled in. We know that a '1' must go somewhere in this region, and the highlighted cell is the only empty cell left!
Similarly for the bottom cell. It is in a region with 5 cells, three of the empty cells are next to the '1' we have just inserted, so the highlighted cell must be a '1'.
We have now arrived at this situation, and we can look at the highlighted cell on the left-hand side of this puzzle. Cells A and B are in a region with two cells, so this region must contain a '1' and '2'. We don't know which way round the 1 and the 2 are in this region, but both possibilities would mean that we can't place a '1' (or a '2') in cell C. This must mean that the highlighted cell is a '1', as all other cells in this region are next to an existing '1'.
It is quite useful to use pencil marks to spot these types of restrictions. It is quite common to apply this type of restriction to a group of cells, which in turn allows you to use a similar technique on another group. This chaining will eventually allow you to enter a number in to a cell.
There is an interesting combination of cells in the bottom-left, I have marked them A, B, C and D. Cells C and D are in their own region of 2 cells, so must contain a '1' and a '2'. Cells A and B are in a larger region containing 5 cells, and one of the numbers left to insert is a '2'. If a '2' was placed in cell A, then that would mean that cells C and D couldn't contain a '2', and that is not possible! This means the '2' must go in cell B.
This allows us to fill cells A, B, C and D.
We are now going to look at the two regions in the bottom middle. The first region has cells A, B, and C. The second region has cells D, E, and F. Both have five cells in total, and both are missing the number '2'.
We can exclude cell A immediately - it has a neighbouring '2'. One of cells D, E or F must be a '2', and all three possibilities mean that cell B can't be a '2'. This means that cell C is the only candidate left, and must therefore be a '2'. (Additionally, cell F can't be a '2' as that would leave the puzzle impossible).
We have a progeessed a little further on our puzzle, can you now work out what should be in the highlighted cell?
You now have all the techniques you need to solve any of our Suguru puzzles. Why not try the Suguru of the day?
We haven't really covered pencil marks here, but all of the more advanced techniques we've used here are easier when used in conjunction with pencil marks.