Puzzles | Cam Dennis Ph.D.

Lucky Charms II

Thu, 20 Jul 2023 00:00:00 +0000

Just a little (kinda hard) puzzle to keep you entertained if you're experiencing ridiculous weather like I am.

Ordinary Sudoku Rules Apply. Additionally:

1. Cells with gray boxes must contain even digits

2. Cells with the lucky charm symbol inside are lucky. The digit inside a lucky charm cell must have that many adjacent and diagonally adjacent neighbors within 1 of the digit. e.g. if a lucky charm cell contains an 8, all 8 of the surrounding cells must be 7, 8, or 9. If it contains a 4, then EXACTLY 4 of the surrounding cells must be 3, 4, or 5.

That's it! Enjoy! :) You can play it here.

Poisson Ratio

Fri, 23 Dec 2022 00:00:00 +0000

Just a little (kinda hard) puzzle to keep you entertained if you're experiencing ridiculous weather like I am.

Ordinary Sudoku Rules Apply. Additionally:

1. Anti-Knight Rules Apply: Cells within a knights move of one another cannot contain the same digit

Renban Rules Apply: Cells on a magenta line must contain consecutive digits (in any order)

German Whisper Rules Apply: Adjacent digits on a green line must differ by at least 5

That's it! Enjoy! :) You can play it here.

Farfalle

Fri, 02 Dec 2022 00:00:00 +0000

I was surprised and delighted when putting together this puzzle. I hope you will be surprised and delighted too!

Ordinary Sudoku Rules Apply. Additionally:

1. Arrow rules apply: Digits along an arrow sum to the digit in the arrow's circle. Digits may repeat on arrows if allowed by other rules

2. Thermo Rules Apply: Digits along each thermometer must increase starting from the bulb end (and digits may not repeat along a thermometer).

3. Knights Move Rules Apply: Digits must not repeat in cells that are a chess knight's move apart.

That's it! Enjoy! :) try it here

Watch a solve from Mark Goodliffe here

Incongruous Simplicity

Sat, 26 Nov 2022 00:00:00 +0000

I just sat down and made this. I've been working on something a little more fun, but wanted to play around in the meantime.

Ordinary Sudoku Rules Apply. Additionally:

1. Arrow rules apply: Digits along an arrow sum to the digit in the arrow's circle.

2. Little Killer Rules Apply: Cells along the indicated diagonals sum to the given value.

That's it! Enjoy! :) You can play it here.

Two For the Show

Tue, 23 Aug 2022 00:00:00 +0000

I've had this break-in idea for a while now. This is just a fun little puzzle. Nothing too extreme.

Ordinary Sudoku Rules Apply. Additionally:

1. Arrow rules apply: Digits along an arrow sum to the digit in the arrow's circle.

2. Kropki Rules Apply: Digits separated by a black dot have a ratio of 1 to 2. Not all dots are necessarily given.

3. Killer Rules Apply: Digits in the box sum to 11.

That's it! Enjoy! :) You can play it here.

Missing Dots

Sat, 09 Jul 2022 00:00:00 +0000

I've always wanted to create a puzzle that makes heavy use of negative constraints. Let me know what you think of this puzzle. It might be an acquired taste.

Ordinary Sudoku Rules Apply. Additionally:

1. Cells that appear in the same position relative to their box form a set of the digits 1 through 9 (Disjoint Groups)

2. The digits 1 through 9 appear on each diagonal exactly once each

3. Digits separated by a black dot have a ratio of 1 to 2

4. Digits separated by a white dot are consecutive

All such dots are given!

That's it! Enjoy! :) You can play it here.

The Guide To Being Cool

Tue, 05 Jul 2022 00:00:00 +0000

Did you folks every draw this weird S thing growing up? This was a huge part of middle school culture in the US (at least for me). Here's the three steps for drawing this. Oh and it's also a puzzle. Enjoy!

Ordinary Sudoku Rules Apply

Additionally, German Whisper rules apply: Adjacent digits along lines must differ by at least 5

That's it! Enjoy! :) You can play it here.

Another Frowning Fish

Thu, 30 Jun 2022 00:00:00 +0000

I think this has an interesting solve path. I hope you enjoy :) Please let me know what you think. I always appreciate the comments!

Ordinary Sudoku Rules Apply. In addition:

1. German Whisper Rules Apply: Adjacent digits on given lines must differ by at least 5

2. XV Sudoku Rules Apply: Digits separated by an X must sum to 10 and digits separated by a V must sum to 5. Not all Xs and Vs are given

That's it! Enjoy! :) You can play it here.

Frowning Fish

Tue, 28 Jun 2022 00:00:00 +0000

I've had this idea for a bit now and I finally got around to making the puzzle. I'm happy with it. Let me know what you think :)

Ordinary Sudoku Rules Apply. In addition:

1. Little Killer Rules Apply: The arrows outside the grid show the sum of the digits along the indicated diagonal

2. Arrow Rules: Digits along an arrow sum to the value in the arrow circle

3. Palindrome Rules: Digits along the gray lines are palindromes reading the same forwards and backwards

4. Kropki Rules: Cells separated by a black dot have a ratio of 1:2 and cells separated by a white dot are consecutive. Not all dots are given.

That's it! Enjoy! :) You can play it here.

Hefty Tiles

Wed, 15 Jun 2022 00:00:00 +0000

Here's an easy little puzzle. I hope you enjoy.

Ordinary Sudoku Rules Apply

Cells along the main diagonal cannot repeat

Cells in shaded boxes are even

Digits on the thick lines form palindromes

The sum of the digits along the indicated diagonals and in the outlined boxes have the same sum and this sum is greater than 30

That's it! Enjoy! :) You can play it here.

Conjunto Conjunto

Wed, 08 Jun 2022 00:00:00 +0000

As I always say, it's been a while since I've made a puzzle. Here's a fun little one. I hope you enjoy.

Ordinary Sudoku Rules Apply

Additionally, cells that appear in the same position relative to their box form a set of the digits 1-9 (Disjoint Groups).

Clues outside the grid give the sum of the digits along the indicated diagonal (digits may repeat if allowed by other rules).

The digits along an arrow sum to the value in the arrow's circle.

That's it! Enjoy! :) You can play it here.

77 Givens

Fri, 19 Nov 2021 00:00:00 +0000

As I always say, it's been a while since I've made a puzzle. Here's a fun little one. I hope you enjoy.

Ordinary Sudoku Rules Apply

In addition, a snake of orthogonally connected cells goes from the upper left green square to the bottom right green square. The snake cannot touch itself orthogonally, but can touch itself diagonally.

Clues outside the grid give the sum of snake cells in the corresponding row or column.

That's it! Enjoy! :) You can play it here.

Arrows and Boxes

Wed, 11 Aug 2021 00:00:00 +0000

It's been quite a while since I've made a puzzle because I've been so busy, but I've been really enjoying some of the gorgeous creations since my last submission. This is just a soft puzzle to share. Hopefully it's fun! :)

Ordinary Sudoku Rules Apply

Ordinary Killer Rules Apply

Ordinary Arrow Rules Apply

That's it! Enjoy! :) You can play it here.

Negative Space

Mon, 01 Mar 2021 00:00:00 +0000

This is the second puzzle I have made with this particular pattern. This one is much harder (in my view) and a much nicer application of the pattern especially given that this is a pure killer sudoku.

Ordinary Sudoku Rules Apply

Ordinary Killer Rules Apply

That's it! Enjoy! :) You can play it here.

It's Gonna Be a Long Knight

Tue, 16 Feb 2021 00:00:00 +0000

The proper name for this puzzle's constraint probably has something to do with taxicab numbers, but I prefer "long knight." Essentially, this is a knight's move constraint with an extra cell. In the explanation image below, none of the green cells can be a 7.

Ordinary Sudoku Rules Apply

Long Knight Rules Apply

Ordinary Killer Rules Apply

Digits may not repeat along the indicated diagonals.

try it here

Watch a solve from Simon Anthony here

Shift-omefel's Theorem

Tue, 05 Jan 2021 00:00:00 +0000

Here is a potentially easy puzzle. The intention is for you to use the shifted version of Phistomefel's theorem. @Narayana refers to Phistomefel's theorem as the Four Lines and Four Boxes theorem (FLFB) which I prefer as well. If you can figure out how to use this theorem, this puzzle is much simpler (as far as I can tell). However, it is almost certainly possible to solve this puzzle without the theorem!

Here is an explanation image. The original theorem is shown where the numbers in the red regions are the same as the numbers in the blue region. However, one may shift the three leftmost columns to the right end of the puzzle to get a new theorem which still works. There are therefore several of these shifted theorems that may prove to be useful.

If you don’t know what I’m talking about, see here.

Ordinary Sudoku Rules Apply

Digits may not repeat on each of the main diagonals

Ordinary Partial Killer Rules Apply

Here is the puzzle. Enjoy! :) try it here

Please let me know if you figured this out with or without using this technique! For added cred, do it both ways ;)

Patchwork Puzzle

Sun, 03 Jan 2021 00:00:00 +0000

The good news is that I cut all of my sudoku puzzles into jigsaw puzzles. The bad news is that I accidentally got them all mixed up. Here are nine pieces from nine different puzzles. Can you put them together to form a new puzzle that has a solution?

Rules:

-Ordinary Sudoku rules apply

-Thermometer rules apply--digits must increase starting from the bulb end of the thermometer

-Little Killer rules apply--digits along the indicated diagonal must sum to the given value and may repeat

-Killer Sudoku rules apply--digits in the cages must sum to the value indicated and may NOT repeat (The digit in the cage is a 13)

-XV Sudoku rules apply--Pairs of cells marked with an X must sum to 10. Pairs of cells marked with a V must sum to 5

Arrow sudoku rules apply--The digits along the arrow sum to the number in the indicated circle.

-Kropki Sudoku rules apply--Cells separated by a black dot must have a quotient of 2. Cells separated by an empty dot must have a difference of 1.

-Sandwich Sudoku rules apply--Numbers outside the grid indicate the sum of the digits between the 1 and the 9 in the indicated row or column. (In this case, the zero is very circular ;)

-Inequality rules apply--The inequality symbol shows which digit is greater.

Additional notes: Note that there are two given digits. One of them is a 1. Additionally, pieces can be rotated, but cannot be flipped upside-down.

Here is the puzzle! Enjoy!

Phistomefel Tribute

Fri, 13 Nov 2020 00:00:00 +0000

Here is a very small and potentially very easy puzzle. The intention is for you to use the 8x8 version of Phistomefel's theorem. Which, as far as I know, is a novel concept. If you can do that, this puzzle is much simpler (as far as I can tell). However, it is almost certainly possible to solve this puzzle without the theorem!

Here is an explanation image.

There are two version of Phistomefel's theorem that show up in this puzzle with non-square regions. In both sides of this image, the red and blue highlighted squares contain the same digits (red=blue). The proof for this follows from the original discovery. If you don't know what I'm talking about, see here.

Ordinary Sudoku Rules Apply

Ordinary Killer Rules Apply

Here is the puzzle. Enjoy! :) You can play it here.

Please let me know if you figured this out with or without using this technique! For added cred, do it both ways ;)

Decoding Killer

Mon, 26 Oct 2020 00:00:00 +0000

Here is another decoding puzzle. Before you begin, it's important to note that this type of puzzle requires a firm grasp of the English language. I sincerely apologize if this excludes you. I promise to make many more puzzles in the future that are more inclusive.

Ordinary Sudoku Rules Apply

Ordinary Little Killer Rules Apply

Ordinary Killer Rules Apply

The killer cages are clues that are needed to solve the puzzle. Some (but not necessarily all) need to be decoded and then read from left to right and top to bottom.

To decode a clue, subtract 26 from it as many times as you can without it becoming negative and then convert that number to it’s alphabetical character (1=a, 2=b, 3=c,…)

Here is the puzzle. Enjoy! :) You can play it here.

276

Mon, 12 Oct 2020 00:00:00 +0000

No complicated rules. Enjoy :)

-Ordinary sudoku rules apply.

-Killer Sudoku Rules apply. Digits cannot repeat in cages and must sum to the number in the top left (if given).

-Little Killer rules apply. The digits in the indicated diagonal sum to the number indicated. Numbers may repeat along each diagonal.

Here is the puzzle. Enjoy! :) You can play it here.

The Killer in the Mirror

Mon, 05 Oct 2020 00:00:00 +0000

When I was young, I was afraid of dimly lit mirrors because I would always see faces in them. It turns out I'm not alone and there's science behind that. You can read about it here.

This puzzle is inspired by that phenomenon.

-Ordinary sudoku rules apply.

-Killer Sudoku Rules apply. Digits cannot repeat in cages and must sum to the number in the top left (if given).

-Looking glass rules (new!) apply. Each digit (1-9) has a "buddy" that appears in all of the cells where the row and column indices are swapped. For example, if 1's are buddies with 4's and there is a 1 in r5c2, then there must be a 4 in r2c5. Ones being buddies with fours implies that fours are buddies with ones. It's possible for a number to be it's own buddy. This rule applies to ALL cells. Figuring out the buddies is part of the puzzle.

This is really a very simple rule, but if you are confused by my explanation or have clarifying questions, please let me know.

Here is the puzzle. Enjoy! :) try it here

Watch a solve from Mark Goodliffe here

Basket Case

Wed, 30 Sep 2020 00:00:00 +0000

This puzzle is patterned after a square lattice or a plain weave.

-Ordinary sudoku rules apply

-Partial killer rules apply (digits in cages cannot repeat and must sum to the total given by the cage)

-Sandwich rules apply (the numbers outside the grid indicate the sum of the digits between the 1 and the 9 in the indicated row or column)

Here is the puzzle. Enjoy! :)

Play it here.

Gaelic Knot

Sun, 27 Sep 2020 00:00:00 +0000

Every puzzle I have posted so far has been an attempt at making inventive new variants. This is just a partial killer-little killer puzzle.

-Ordinary sudoku rules apply

-Partial killer rules apply (digits in cages cannot repeat and must sum to the total given by the cage)

-Little Killer rules apply (digits outside the grid indicate the sum of the digits along the marked diagonal. Digits may repeat).

Here is the puzzle. Enjoy! :)

Try it here.

Origami Sudoku

Thu, 24 Sep 2020 00:00:00 +0000

I had an unsolved 1 star sudoku puzzle that I accidentally left folded up on my desk. I asked someone to scan it and email it to me but they didn't unfold it before doing so! Can you still solve this 1 star puzzle?

-Ordinary sudoku rules apply

-Note that the 3 and 8 are symmetric across the horizontal axis

-Note that you can't actually tell which number is on top of a pile

To make things easier, here is how I folded the puzzle

Here is the puzzle as well as a sample of my handwriting. Enjoy! :)

Looking Glass Thermo

Fri, 18 Sep 2020 00:00:00 +0000

My previous puzzle with this theme seemed to go over pretty well, so I've made another. Again, this one is not too terribly difficult, but I think quite fun.

-Ordinary sudoku rules apply.

-Thermometer rules apply. Digits must strictly increase along thermometers starting from the bulb end.

This is really a very simple rule, but if you are confused by my explanation or have clarifying questions, please let me know.

try it here

Through the Looking Glass

Tue, 01 Sep 2020 00:00:00 +0000

As far as I know, this is a novel variant with some very interesting logic.

-Ordinary sudoku rules apply.

-Little killer rules apply. The arrows indicate the sum of the digits in the direction of the arrow. Some sums may contain the same digit more than once.

This is really a very simple rule, but if you are confused by my explanation or have clarifying questions, please let me know.

try it here

Watch a solve from Mark Goodliffe here

Decodoku

Mon, 24 Aug 2020 00:00:00 +0000

This is an extremely easy coffee break puzzle, so it should be fun way to spend a few minutes.

Ordinary sudoku rules apply. In addition, there are a few cages which once filled can be decoded. Take the two numbers in the cage and subtract 26 as many times as you can (take the caged number modulo 26). The result represents that letter of the english alphabet.

Take for example the number 91. If we subtract 26 from this we get 65, then 39, and finally 13. The thirteenth letter of the english alphabet is m.

Finding the (English) decoded message is necessary to solve the puzzle.

Note: If you don’t feel like converting numbers to letters, use this online tool.

try it here

Time in a Bottle

Thu, 20 Aug 2020 00:00:00 +0000

If I could make days last forever

If words could make wishes come true

I'd save every day like a treasure and then

I'd play sudoku with you

Enough of that. This puzzle was made as a tribute to one of my favorite musicians, Jim Croce. The song can be found here. The inspiration for this puzzle comes from everyone's favorite setter, Richard. His original clock sudoku can be found here.

This is the third in a series of puzzles that are played on a Klein Bottle.

Ordinary sudoku rules apply. This puzzle takes place on a klein bottle. The top and bottom of the grid are glued together--they obey periodic boundary conditions (see the example on the left). The left and right side are twisted and then glued together (see the right side). The circles in the grid represent clocks. The four digits surrounding a white clock must strictly increase in a clockwise fashion starting from any of the four cells. The four digits surrounding a black clock must strictly increase in an anti-clockwise fashion starting from any of the four cells. All possible clocks are marked. (Don't forget the negative constraint!) Let me know if anything is unclear in the comments :)

Here is the puzzle. Enjoy! :)

Here is a penpa link courtesy of panthchesh. Thank you!

Klein Bottle Sudoku

Fri, 14 Aug 2020 00:00:00 +0000

This is the second in a series of puzzles that are played on a Klein Bottle. If you like this idea, please let me know.

Ordinary sudoku rules DO NOT apply. Please read carefully. This puzzle takes place on a klein bottle. The top and bottom of the grid are glued together--they obey periodic boundary conditions (see the example on the left). The left and right side are twisted and then glued together (see the right side). The little klein bottles denote the separation of two horizontal 9 square "klein rows." Each column and box behave normally. Every column, box, and klein row must contain the digits 1-9 exactly once. You may notice that the 1's in the puzzle are in the same "ordinary row" but they are separated by a klein bottle and are therefore in different klein rows. Let me know if anything is unclear in the comments :)

Here is the puzzle. Enjoy! :)

Klein Bottle Magic Square Puzzle

Wed, 05 Aug 2020 00:00:00 +0000

I am making this puzzle for my friend James. It's his birthday! This is the first in a series of puzzles that are played on a Klein Bottle. This is a little bit of an introduction to the concept, but be on the lookout for some really cool variants to come. If you like this idea, please let me know.

Ordinary sudoku rules apply. In addition, colored squares are the centers of 3x3 magic squares. A magic square is a box that contains the numbers 1 through 9 exactly once and where the rows, columns, and main diagonals all sum to the same number. This puzzle also takes place on a klein bottle. The top and bottom of the grid are glued together--they obey periodic boundary conditions (see the example on the left). The left and right side are twisted and then glued together (see the right side). Let me know if anything is unclear in the comments :)

try it here

Lucky Charms Sudoku

Sun, 26 Jul 2020 00:00:00 +0000

This is the first in what may become a series of puzzles with a constraint I call lucky charms. This is based on one of my all time favorite sugary breakfast cereals from the US. This puzzle is rather easy but I hope that doesn't prevent you from enjoying it because I think you'll find that it has some really neat logic. If you like this variant, please let me know.

Ordinary sudoku rules apply. In addition, some cells are lucky charms. Each lucky charm symbol represents a different number. The digits near the lucky charm (adjacent and diagonally adjacent) that are within 1 of the lucky charm's number are called close neighbors. For example, if the lucky charm is 4, any neighboring digits that are 3, 4, or 5 are close neighbors. See the example below where these are highlighted. A lucky charm has exactly as many close neighbors as it's number. In the below example, there are two 3's, a 4, and a 5 for a total of 4 close neighbors.

All lucky charms are given (so negative constraints may be necessary).

try it here

Thermo Princesses

Sun, 12 Jul 2020 00:00:00 +0000

This is the third in a series of puzzles with a constraint I call princesses. If you like this variant, feel free to check out the others.

Ordinary sudoku rules apply. In addition, the number in a box tells you the minimum diagonal distance between another of the same number. In the below example, I have marked the boxes that cannot be 3's in magenta. You'll notice that 1's have no additional constraint and 9's will act like queens. Every other number will behave like something inbetween.

In addition, thermo-sudoku rules apply: numbers in thermometers must increase starting at the bulb end. It was suggested to me (by RockyRoer) that using the princesses constraint would be slightly nicer if the grid had a light checkerboard pattern. This is for convenience and is not part of the puzzle clues.

Here is the puzzle. Enjoy!

try it here

Clone Miracle Sudoku

Fri, 19 Jun 2020 00:00:00 +0000

This puzzle is very clearly inspired by Mitchell Lee's famous Miracle Sudoku and is a bit of low hanging fruit.

The rules are the same as the miracle sudoku rules: Cells separated by a King's move or a Knight's move cannot contain the same digit. Orthogonally adjacent cells cannot contain consecutive digits. The gray regions are clones of one another.

try it here

Enjoy!

Little Killer Princesses

Thu, 18 Jun 2020 00:00:00 +0000

This is a follow up little killer version of my previous puzzle. And my very first puzzle with no given digits!

try it here

Kings, Queens, and Princesses

Fri, 12 Jun 2020 00:00:00 +0000

The numbers in this puzzle have a constraint I call anti-princess

Rules:

Enjoy!

try it here

Watch a solve from Mark Goodliffe here

4x4 Magic Square

Tue, 09 Jun 2020 00:00:00 +0000

Rules:

This magenta box is a 4x4 magic square that has been tilted 45 degrees. This magic square must contain the numbers 1 through 16 exactly once and each row, column, and main diagonal of the magenta box must have the same sum. Any number in the magic square that has two digits must be entered as the sum of it's digits. For example, one of the 5's in the magenta box must actually be a 14. Beyond this, regular sudoku rules apply. Have fun! try it here

Watch a solve from Mark Goodliffe here

Kings, Knights, or Queens

Mon, 25 May 2020 00:00:00 +0000

Try it EITHER as King Sudoku (identical digits cannot be a chess king’s move apart) OR Queen Sudoku (9s cannot be a chess queen’s move apart) OR Knight Sudoku (identical digits cannot be a knight’s move apart)

NOTE: Because this puzzle has multiple solutions, the answer check function will not work.

try it here

Watch multiple solves of this puzzle from Mark Goodliffe here and here

Goldilocks Sudoku

Tue, 09 Jun 2020 00:00:00 +0000

This is the Goldilock's puzzle. It has 3 solutions. The first and easiest solution is found after placing a 1 in the central gray box. Placing a 2 in the box gives a moderately difficult solve. Placing a 3 in the central box gives a difficult solve.

Rules:

After placing your chosen number in the central box, normal sudoku rules apply.

Enjoy!

try it here or watch a solve from Mark Goodliffe here