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Sudoku Puzzles

Play some of my sudoku variant puzzles here.

I have had a passing interest in sudoku and killer sudoku puzzles for some time. During the Coronavirus lockdown I discovered the Cracking The Cryptic YouTube channel. This opened up to me a whole new world of sudoku variant puzzle types that I had been completely unaware of.

The CtC channel and the CtC fan discord server have also helped improve my knowledge of sudoku solving techniques, although I am still pretty bad at it. Most of the puzzles that I make, I would probably not enjoy solving very much myself. I make mistakes easily and get frustrated when I go wrong. I tend to prefer slightly easier puzzles, but when setting puzzles, I do like to try to make the solver do a bit of work to find the solution.

Classic Sudoku

Many sudoku puzzles nowadays that you find in newspapers (and websites that offer lots of puzzles) will be computer-generated. These can be OK but some of them aren't much fun. The best puzzles are those that have been hand-crafted by a real person as you know there will be some interesting logic involved that has been specifically designed into the puzzle, rather than a computer just randomly putting in clues according to some algorithm. The best human setters will place the given digits in such a way as to lead you through the solve in a satisfying way, or they will present the clues helpfully in order to telegraph that a particular technique is required or to subtly point you in the right direction.

Most of the puzzles I have made have been variant puzzles. i.e. there are rules or constraints additional to the normal sudoku rules. I find classic sudoku very difficult to set. Sudoku variants with additional constraints gives me more options to make puzzles interesting.

Currently I just have the one classic sudoku puzzle. It is not too difficult if you know some of the basic techniques. I did get some nice comments on this puzzle in the CtC fan discord server.

[Classic Sudoku]

Sandwich Sudoku

One of the standard sudoku variants that I enjoy is known as Sandwich Sudoku, or Between 1 and 9 Sums. I have written quite a number of puzzles combining sandwich sums with other variant rulesets. Here are a few that are straightforward sandwich sudoku without any additional rules.

[Sandwich Sudoku] [Sandwich Sudoku] [Sandwich Sudoku]

Combining sandwich rules with Kropki Pairs

Kropki is the polish word for dots. Kropki Pairs Sudoku have dots between squares. A white dot indicates that the two squares have a difference of 1, i.e. they contain consecutive digits. A black dot indicates that the two squares have a 2:1 ratio, i.e. one digit is half the value of the other.

[Kropki Pairs Sandwich Sudoku]

Combining sandwich rules with Sudoku Arrows

In Arrow Sudoku some cells in the grid containing a circle, and each circle has one or more attached arrow. The sum of all the digits along an arrow always equals the value of the digit in the circle.

[Arrow Sandwich]

Combining sandwich rules with Between Lines

Between Lines is an interesting variant constraint. Lines connect two cells, each of which contains a circle. The digits in the squares that the line passes through are always 'in between' the two digits in the circle. i.e. one of the circles contains a digit higher than every digit on the line, and the other contains a digit smaller than the digits on the line.

[Between Lines Sandwich]

More Than Sandwich

Here are a couple that combine sandwich sudoku with inequality signs between squares. These tell you which of the two squares is the largest.

[More Than Sandwich Sudoku] [More Than Sandwich Sudoku]

Combining sandwich rules with Thermos

Thermometers (aka Thermos) in sudoku are a bit like inequality signs. Digits along a thermometer must strictly increase, starting with the lowest digit in the bulb.

[Casket of Gold]

Sandwich rules with misplaced clues

Sometimes puzzle setters like to be a bit sneaky and move the clues somewhere else in the grid than where they are supposed to be. There will be some logical way to find out the correct placement though and solve the puzzle.

[Broken Sandwich Sudoku]

Sandwich rules with crypto-clues

Crypto-clues are given digits, sandwich sum values, or other clues where the numbers (or each digit in 2-digit numbers) is replaced with a letter of the alphabet. So, in order to solve the puzzle you will need to also figure out which letter represents which digit.

These can be quite fun as the letters can sometimes make words in the grid. I have found this useful when making puzzles with a specific theme. e.g. for the Monthly CtC discord server puzzle prompt.

Some of these puzzle also have killer cages or other variant constraints to help you solve the puzzle.

[Killer partridge in a pear sandwich] - featured on CtC with Simon Anthony
[New Year's Resolutions]
[Creepy Crawlies Are Scary] - featured on CtC with Mark Goodliffe
[Bicycle Repair Man]
[Super hero sudoku]
[Fairy Chess Sudoku]

New variants of my own devising

I have come up with a couple of ideas for potential new variant sudoku puzzles. To my knowledge, no-one else has yet taken up my ideas and produced their own puzzles using these rules. You may still find these puzzles interesting though. Please let me know if you enjoy these puzzles and especially if you have a go at creating your own puzzles using these rules.

Difference Arrows

This is a variation on arrow sudoku. Normally the digits along an arrow sum to the value in a cell containing a circle that is attached to the arrow. In this variant, when there are two arrows from the same circle, the value in the circle is the difference between the two arrow sums.

[Difference Arrows] [More Difference Arrows] [Difference Arrows - first version]

Find The ➕

In this new variant you have to imagine a plus sign between two cells in a row or column of the grid. When read left to right in the row or top to bottom in this column, this results in a sum of two numbers. The outside clue gives the result of this sum.

[4x4 taster puzzle] [Find The ➕ No 1] [Find The ➕ No 2]

Other Puzzles

[Ambiguous Kropki Sudoku]
[Modern Art Sudoku - Mondrian]
[Modern Art Sudoku - Dali] - featured on CtC with Mark Goodliffe
[Modern Art Sudoku - Van Gogh
[Smaller is bigger]
[Ambiguous Thermometer Sudoku]
[Because I'm Mad]
[What is Wrogn?]
[9 5794 9338945]
[Trick or Treat Sudoku]


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Phil's Puzzles Page
I have always had a passing interest in puzzles, but this has become a bit more of a serious obsession during lockdown since I discovered the Cracking The Cryptic YouTube channel.
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Classic Sudoku
This is my attempt at setting an ordinary classic sudoku puzzle.
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Sandwich Sudoku
I had made a few puzzles combination sandwich sudoku with crypto clues and other rules. So I decided it would be a good idea to make a few more straightforward sandwich sudoku puzzles. This was my first.
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Sandwich Sudoku
This is the second in a series of sandwich sudoku puzzles.
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Sandwich Sudoku
This is the fourth in a series of sandwich sudoku puzzles.
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Kropki Pairs Sandwich Sudoku
I have written quite a few sandwich sudoku puzzles. This one combines sandwich rules with Kropki Pairs.
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Arrow Sandwich Sudoku
This puzzle combines sandwich sudoku and arrow sudoku. I am quite pleased with the symmetrical arrangement and aesthetics of the clue placements and given digits. The broken arrow idea is quite fun too I think.
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Between Lines Sandwich Sudoku
I have written quite a few sandwich sudoku puzzles. This one combines sandwich rules with Between Lines.
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More than sandwich sudoku
I have made quite a few sandwich sudoku puzzles. This one combines 'Greater Than' rules with normal sandwich sudoku rules.
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More than sandwich sudoku
I quite liked my first 'More than sandwich sudoku' so I thought I would make another.
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Casket of Gold
This puzzle was created for the April 2021 monthly puzzle prompt in the CtC fan discord server. The theme was Fool's Gold.
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Broken Sandwich sudoku
This puzzle is one that I created for the January 2021 monthly puzzle prompt in the CtC fan discord server. The joke is that the grid has broken, causing the sandwich clues and given digits to have all slid down to the bottom.
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Killer partridge in a pear sandwich
This is the first one of my puzzles to be featured on Cracking The Cryptic. I was amazed that Simon chose my puzzle to solve on Christmas Day. I created this for the December 2020 monthly puzzle prompt in the CtC fan discord server. The theme was the 12 days of Christmas.
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New Year's Resolutions - The Sudoku
This puzzle was a follow up to my Christmas puzzle that was featured on the Cracking The Cryptic YouTube channel. It is a combination of killer sudoku and sandwich sudoku with crypto-clues (i.e. some digits have been replaced with letters which have to be determined in order to solve the puzzle.
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Creepy Crawlies Are Scary
This puzzle was created for the February 2021 monthly puzzle prompt in the CtC fan discord server. I was very surprised and honoured to have this puzzle solved by Mark Goodliffe and featured on the Cracking The Cryptic YouTube channel.
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Bicycle Repair Man
This puzzle was created for the March 2021 monthly puzzle prompt in the CtC fan discord server. The theme was superheros. The title of this puzzle references a classic sketch from Monty Python's Flying Circus.
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Super hero sudoku
This puzzle was created for the March 2021 monthly puzzle prompt in the CtC fan discord server. Can you solve the puzzle and reveal the name of this hero who had been in the news recently at the time?
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Fairy Chess Sandwich Sudoku
This puzzle was originally intended for the May 2021 monthly puzzle prompt in the CtC fan discord server. However, I didn't get it finished in time so I found a way to fit the theme of the June puzzle prompt instead.
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Difference Arrows
This is a new idea for a sudoku variant puzzle adapted from standard Arrow Sudoku. Please give it a try and let me know what you think. In normal arrow sudoku the number in the circle is equal to the sum of the digits along the arrow. In this variation, each circle has two arrows and you take the difference of the two sums.
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More Difference Arrows
This is another puzzle using difference arrows. This one has no given digits to start you off but shouldn't be too much harder. Please give it a try and let me know what you think.
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Difference Arrows (first version)
This was my first attempt at a new idea for a sudoku variant puzzle adapted from standard Arrow Sudoku. In this variation, some circles have two arrows and for these you take the difference of the two sums.
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Find The + (4x4 taster)
This is a small taster puzzle to try out the idea for a new sudoku variant ruleset. In the puzzle you must imagine a plus sign between two of the digits in a row or column. This results in two separate numbers, one either side of the plus sign. the sum of the two numbers must add up to a number given by a clue outside the grid.
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Find The + No. 1 - a new variant
This is a new sudoku variant puzzle created for the June 2021 monthly puzzle prompt in the CtC fan discord server. In this puzzle you must imagine a plus sign between two of the digits in a row or column. This results in two separate numbers, one either side of the plus sign. the sum of the two numbers must add up to a number given by a clue outside the grid.
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Find The + No. 2
This is a follow-up to my first Find The + puzzle and uses the same ruleset. In the puzzle you must imagine a plus sign between two of the digits in a row or column. This results in two separate numbers, one either side of the plus sign. the sum of the two numbers must add up to a number given by a clue outside the grid.
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Ambiguous Kropki Sudoku
This is a variation on kropki sudoku. Usually black and white dots are used to indicate cels that have a 2:1 ratio or a difference of 1. In this puzzle all the dots have been replaced with smiley faces, so you need to work out which are which.
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Sudoku with Red, Yellow and Blue
This puzzle is another that I created for the November 2020 monthly puzzle prompt in the CtC fan discord server.
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La Persistencia del Sudoku
This is the second puzzle I created for the November 2020 monthly puzzle prompt in the CtC fan discord server.
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Sumflowers
This puzzle was made for the November 2020 monthly puzzle prompt in the CtC fan discord server which was on the theme of modern art.
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Smaller is bigger - The Sudoku
This is basically a killer sudoku puzzle but where the cage totals are not given and must be determined. The grid also contains a magic square, a diagonal constraint and some other rules to help solve the puzzle.
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Ambiguous Thermometers
This puzzle is a bit different to my usual puzzles. The idea came about following a discussion in the Ctc fan discord server which somehow got onto the subject of thermometers, and whether they should be in Celsius or Fahrenheit.
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Because I'm Mad
This puzzle was inspired by the norinori craze on the CtC discord server after Simon did a norinori-sudoku hybrid puzzle. My puzzle is a bit different. It combines sudoku, norinori, sandwich and crypto-clues as well as magic squares, etc... - so is a bit of a mash-up. Hopefully a fun puzzle though. Please try it and let me know.
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What is Wrogn?
Can you find what is wrogn and solve the puzzle? This was inspired by DiMono's puzzle: Everything is Wrogn!. In my puzzle, there is only one of the rules that is 'wrogn' but you have to figure out which it is.
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9 5794 9338945
This puzzle was made as a Christmas gift in the CtC fan discord server secret santa. I am still not sure if the person I made this puzzle for actually knows that it was me who created it. They did say some nice things about the puzzle though.
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T or T
Pumpkins are usually a Treat but someone has played a trick and some of them aren’t! Can you find which are a Trick or a Treat and use this to complete the puzzle? This puzzle was made for the October 2020 monthly puzzle prompt in the CtC fan discord server which was on the theme of Halloween.
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Phil's Crossword Puzzles
Here are a few crossword puzzles that I have written.
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