1. Carried Away
Normal sudoku rules apply (fill each row, column, and 3x3 box with the digits 1-9 once each), and all clues are standard.
Cages: the sum of the digits inside each cage is equal to the small number in the top left corner.
Thermometers: digits on thermometers increase from the bulb.
Very rough difficulty estimate: 3/10
Play online: SudokuPad | unshaded
New to variant sudoku? Check out these beginner-friendly guides to killer cages and other popular rulesets.
2. Avoision
Normal sudoku rules apply (fill each row, column, and 3x3 box with the digits 1-9 once each), and all clues are standard.
Cages: the sum of the digits inside each cage is equal to the small number in the top left corner.
Arrows: the sum of the digits along an arrow is equal to the digit in the connected circle, and these digits can repeat if allowed by other rules.
Very rough difficulty estimate: 6/10
Play online: SudokuPad | unshaded
So, I generally stick to “standard” variant sudoku rulesets, especially for the free puzzles, and I realize column indexing—sometimes referred to as 159, since those are typically the digits being indexed—may be a little unfamiliar for many of you. But it’s one of my favorite rulesets, and this is Volume 159, so I hope I can be excused for being a little indulgent 😁
As a gesture of goodwill, I’ve provided an illustration and a few tips below.
3. One Fog Nine
Normal sudoku rules apply (fill each row, column, and 3x3 box with the digits 1-9 once each).
Dynamic fog: correctly placed digits clear the fog from that cell, and possibly from other cells.
Indexing: digits in columns 1, 5, and 9 indicate the column in which the digit 1, 5, or 9 (respectively) appears in that row. Index cells are shaded red.
Example: if the digit in r3c1 is 7, then the 1 in row three is in column seven, i.e. r3c7.German whispers: along green lines, digits differ from their neighbors by at least 5.
Digits in cells separated by a white dot are consecutive.
Digits in cells separated by a black dot have a 1:2 ratio.
Very rough difficulty estimates: 7/10, 5/10
Play online: SudokuPad | no fog
Extra clues: SudokuPad | no fog
Fog-free versions are provided because dynamic fog may not be supported on all versions of SudokuPad (and simply because some solvers may prefer it that way). If anything, I think those versions might be slightly *tougher*, because the solve path is less focused.
Some tips, using the layout below:
The 7 in r3c1 means the 1 in row three is in column seven (i.e. r3c7), and the 2 in r3c5 means the 5 in row three is in column two (i.e. r3c2).
An index digit in its own column (e.g. 5 in r1c5) simply indexes itself, providing no information about other digits.
Information can be gleaned from placing digits in index cells, and also from placing 1, 5, or 9 in other columns. Here, the 9 in r1c3 means there must be a 3 in r1c9.
Any set of three index digits in the same box must include a low digit (123), a middle digit (456), and a high digit (789); otherwise, the digit being indexed would repeat in a box.
As an example of that here, consider whether the digit in r2c5 can be anything other than 7, 8, or 9. If it’s low, 5 would repeat in box one, and if it’s a middle digit, 5 would repeat in box two, so it must be high.
Some other puzzles I enjoyed this week:
Sting in the Tail, by Timotab
Ramify, by dumediat
Mousetrap?, by Tallcat
And, because Volume 159 only comes around once, if you want more indexing puzzles, I’ll suggest:
Eye of Agamotto, by Allagem
Competitive Tetris, by BremSter
and one of mine, 159 Miracle
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This week’s meta-description:
I can’t be bothered to plan ahead for holidays, but when there’s a volume number that happens to share a name with one of my favorite rules? That’s been on my radar for months.
For premium subscribers, hints and two more bonus puzzles are below. Could I resist the urge to include one more 159 puzzle? No, I could not.
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