Today I present a wonderful new type of Sudoku, invented by reader Alf Smith. Like all Sudokus, numbers 1-9 must appear in all rows, columns and boxes.
However, the difference between this new variant is that there are no clues in the starting grid. Instead, some cells are golden. Additional rules include numbers for gold cells. position Either the column, column, or box of that cell (left to right, top to bottom read).
Check out our 6×6 tutorial. (After that there are two 9×9 puzzles. To print all three puzzles, click here for pdf. )
1.
Gold cell numbers describe the position of either a column, column, or box. So, in the box on the top left, the gold cell in the first column must be either 1 (row position 1), 2 (column position 2), or 4 (block position 4). Possible numbers have been added to the gold cells in the top two rows of the diagram below. To clarify the location of cells within the box, they do 1-2-3 in the first row and 4-5-6 in the second row.
Okay, let's get started:
Step 1. All columns contain all digits, so the second column has 2. It needs to go to gold cells. Because if it enters a white cell it is described as being 2 in columns. (If the number explains that it is a position, the cell must be gold.) Similarly, the 4 in column 4 can only go to the gold cell.
Step 2. Row 6 4 (red marked) can only go to column 6. None of the sixth squares are in the fourth position, so you cannot go to the gold square on line 6. And since these squares are at position 4 of the box, you cannot go to the other white squares in line 6. This means that the number explains its location.
What I like about these puzzles is that to solve them you need to think about what you can't put in a cell, as well as what you can't.
Step 3. In column 6, I put all the numbers that could enter gold cells. Since there are already four in row 6, the cells in row 4 must be 6 (red mark) and the cells in row 2 must be 2 (red again). Line 5 must be either 3 or 5. I guess that the other other free spaces in the column are white, at box position 3, and should be 3, to give inconsistencies.
That's enough! To you now.
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3.
I'll be back at 5pm in the UK with the solution. There are no spoilers.
Here's the link to print them all over again.
Alf calls his puzzle Posidoku. Do you think there might be a catchy title, like the ignorant Sudoku, or Golden Snok? Add your ideas below! Make this puzzle classic.
I've been setting up a puzzle here on alternative Mondays since 2015. I'm always looking for great puzzles. If you would like a suggestion please email me.
