Is that a Face in my Grid? Solvers who commented on youtube, and who spotted something that should be considered obvious, solved it in between 13 and 35 minutes.
Note: many, if not most, of these puzzles use non-traditional markup for the grid furniture, which is alas a function of the tool I use to draw them. Apologies.
Normal sudoku rules apply. All cages, denoted by a non-white region enclosed by a greenish border, have the same sum, and may not contain repeated digits. All cages have different contents. Orange crosses are White Kropke Dots, the cells have a difference of one. Black crosses are Black Kropke Dots, one of the cells is double the other. Partial negative contstraint - within cages, all kropke dots are given. Colours mean nothing, they're just to make the cages clearer.
Difficulty: 2/5. Time: 30-40 minutes.
Solution here, worked solution here
Normal sudoku rules apply. All cages, denoted by a non-white region enclosed by a greenish border, have the same sum, and may not contain repeated digits. All cages have different contents. Orange crosses are White Kropke Dots: the cells have a difference of one. Black crosses are Black Kropke Dots: one of the cells is double the other. Partial negative contstraint - within cages, all kropke dots are given. Colours mean nothing, they're just to make the cages clearer.
Difficulty: 1/5-2/5. Time: 25-30 minutes.
Play, with traditional graphics for the furniture, in Sven's amazing SudokuPad here.
Solution here, worked solution here. Aside: "magoo" is nothing to do with Mark, it's a reference to how code golfers sometimes blindly modify their code to make it smaller, a technique I used to help fit in all the cages.
Cracking the Cryptic
(specifically Mark ("Magoo") featured this puzzle on 2025/03/26:
Is that a Face in my Grid? Solvers who commented on
youtube, and who spotted something that should be considered
obvious, solved it in between 13 and 35 minutes.
Normal sudoku rules apply. The numbers outside the grid are the sum of the longest possible Thermometer that could be drawn in the grid perpendicular to that edge, with its bulb in the edge cell. Digits in Thermometers increase in value along their length away from the bulb.
Difficulty: 1/5-2/5. Time: 25-30 minutes.
Solution here, with some colour marking the thermos here, and a worked solution here.
While I was getting some practice to help me with the next puzzle, Shy Thermopile, I enjoyed solving a bunch of these - here are a few of my favourites.
Normal sudoku rules apply. The numbers outside the grid are the sum of the longest possible Thermometer that could be drawn in the grid perpendicular to that edge, with its bulb in the edge cell. A bulb with no shaft is not a real Thermometer, and in precisely those cases no sum is listed. As always, digits in Thermometers increase in value along their length away from the bulb. The glyph in the corner of box 5 is a thermometer of 2 cells. The shading in some of the edge cells corresponds to the lack of a real Thermometer starting in that cell and lack of number outside the grid, it is purely cosmetic.
Difficulty: 2/5-3/5. Time: 40-50 minutes.
Solution here, with some colour marking the thermos here, and a worked solution here.
I enjoyed solving a bunch of these - here are a few of my favourites.
Normal sudoku rules apply. The numbers outside the grid are the sum of the longest possible Thermometer that could be drawn in the grid perpendicular to that edge, with its bulb in the edge cell. A bulb with no shaft is not a real Thermometer, and in precisely those cases no sum is listed. As always, digits in Thermometers increase in value along their length away from the bulb.
Difficulty: 2/5-3/5. Time: 45-60 minutes.
| 14 | - | - | 15 | - | 16 | - | 12 | - | ||
|---|---|---|---|---|---|---|---|---|---|---|
| 17 | - | |||||||||
| - | 11 | |||||||||
| - | - | |||||||||
| 14 | 10 | |||||||||
| 21 | 17 | |||||||||
| 4 | 14 | |||||||||
| - | - | |||||||||
| 11 | - | |||||||||
| - | 11 | |||||||||
| - | 12 | 12 | - | - | - | - | - | 14 |
Solution here, and a worked solution here.
Normal sudoku rules apply. The products of the diagonals in the marked 2x2 squares sum to 38. (E.g. if row 8 began 12..., and row 9 began 34... the 2x2 square would have diagonals 1*4 and 2*3, which sum to 10, which would be in error, as that's not 38!) No two such squares contain the same 4 digits.
Difficulty: 3/5. Time: 60-75 minutes.
Solution here, and a worked solution here, which also briefly explains why I didn't need to tell you that the sum is 38.
Note: I consider this puzzle to be inferior to the Reduxed and Minimal versions below.
Normal sudoku rules apply. Blue crosses are ambiguous double/triple kropke dots, one of the cells is either double or triple the other. Black Xs connect cells that sum to 10. Black lines connect consecutive numbers in the Fibonacci sequence - all possible lines are marked.
Difficulty: 2/5. Time: 35-45 minutes.
Solution here, and there's a worked solution.
Normal sudoku rules apply. Blue crosses are ambiguous double/triple kropke dots, one of the cells is either double or triple the other. Black Xs connect cells that sum to 10. Black lines connect consecutive numbers in the Fibonacci sequence - all possible lines are marked.
Difficulty: 1-2/5. Time: 25-35 minutes.
Solution here and there's also a worked solution.
Normal sudoku rules apply. Blue crosses are ambiguous double/triple kropke dots, one of the cells is either double or triple the other. Black Xs connect cells that sum to 10. Black lines connect consecutive numbers in the Fibonacci sequence - all possible lines are marked.
Difficulty: 1/5. Time: 25-35 minutes.
Solution here, and there's also a worked solution.
Normal sudoku rules apply. Green lines are German Wispers: adjacent cells must differ by at least 5. Cells with an X between them sum to 10. Of course, there's a 3 in a corner.
Difficulty: 2/5. Time: 30-40 minutes.
Solution here, and there's also a guide to solving, containing the essential insights on how to crack it.
Normal sudoku rules apply. Circles indicate there is a cell of the same value along a diagonal at a distance equal to that value.
Difficulty: 1/5. Time: 10-15 minutes
Solution here, and without any furniture visible here. Unusually, I provide no guided solution, as no great insights are required. It's just intended to be a fun speedrun.
Normal sudoku rules apply. Brown lines connect cells that sum to 5. Black crosses connect cells that sum to 10. All such sums are marked. The centre box is a magic square.
Difficulty: 2/5. Time: 40-60 minutes
Solution here, and without any colours here. No walk-through, but here are some hintscreated for an almost identical puzzle that got tweaked.
Normal sudoku rules apply. The big gold stars are German Whispers, neighbouring cells must differ by at least 5. The pink twinkles are white kropke dots, the cells must differ by 1. The grey twinkle is a black kropke dot, one cell must be double the other.
Difficulty: 2/5. Time: 35-50 minutes
Solution here, and without any colours here. Here's a walked-through solution.
Note: This one eases you in more slowly than the almost-identical version II, but the bulk of the solve follows the same pattern.
Normal sudoku rules apply.
Blue lines are Renban Lines, consecutive numbers in any order.
Yellow lines are Modular Lines, cells with the same value remainder 3 must not be fewer than 3 cells apart. (So 1-5-6-4 is fine, but 2-6-8 isn't.)
Dark green lines are Entropy Lines, cells in the same low (123), mid (456), and high (789) bands must not be fewer than 3 cells apart. (So 2-8-4-3 is fine, but 4-3-1 isn't.)
Black crosses are Black Kropke Dots, one cell must be double the other.
The brown cross is a White Kropke Dot, it connects two cells that differ by one.
Difficulty: 1/5-2/5. Time: 40-60 minutes
Solution here, and without any colours here. Here's a walked-through solution.
Note: This one has a tougher speedbump at the start, and leaves certain symmetries unresolved till later than the almost-identical original version, but the bulk of the solve follows the same pattern.
Normal sudoku rules apply.
Blue lines are Renban Lines, consecutive numbers in any order.
Yellow lines are Modular Lines, cells with the same value remainder 3 must not be fewer than 3 cells apart. (So 1-5-6-4 is fine, but 2-6-8 isn't.)
Dark green lines are Entropy Lines, cells in the same low (123), mid (456), and high (789) bands must not be fewer than 3 cells apart. (So 2-8-4-3 is fine, but 4-3-1 isn't.)
Black crosses are Black Kropke Dots, one cell must be double the other.
Brown crosses are White Kropke Dots, connecting two cells that differ by one.
Difficulty: 2/5. Time: 50-70 minutes
Solution here, and without any colours here. Here's a walked-through solution.
Normal sudoku rules apply.
Numbers in circles indicate how many of that number are in circles.
The sum of the values along a line is equal to the sum of the two values in the circles.
Difficulty: 3/5. Time: 50-90 minutes
Solution here, and without colours here. A walked-through solve is here.
Note: The puzzle was designed to frustrate normal solving techniques, so I provide a hint that might make solving simpler.
Many of the image herein are created using Sven's amazing SudokuPad, which is how I play the puzzles that /Cracking the Cryptic/ point me towards.
Some others have been created using another online tool that I will link to later...
Another hastily constructed page by Phil Carmody
FatPhil.org / Sudoku / index.html
