Daily League Sudoku #27: Thermo-Sudoku

I promised something easier this week and I think this should be good. This Thermo-Sudoku has a simple opening that should give away a few quick digits. I was trying to make it without any given digits, but the given layout wouldn't allow it. The one central 5 made it unique though and it fits with the decreasing size of squares. It might be possible to line up the thermometers to make it unique without digits or by adding an extra one in the center, but I like how it turned out. I just hope I haven't misjudged the difficulty again, as I have done before. Enjoy.

Recap of the last Daily League week:
Sunday: Alternative Sudoku by Seungjae Kwak
Tuesday: Even Sudoku with Disjoint Groups by Prasanna Seshadri
Wednesday: Arrow Sudoku by Bastien Vial-Jaime
Thursday: 1-Consecutive Sudoku by Hall Hur
Friday: Irregular Sudoku by Tom Collyer

All puzzles can also be solved at SudokuCup.

Rules for Sudoku

In this Sudoku, there are a number of thermometers. Along each thermometer, digits have to be strictly increasing from the bulb upwards.

TVC XIV Practise: Part 2

This post is a bit delayed. That happens when you discover mistakes in your puzzles. I think I fixed them, but sometimes you just get stuck in a spiral of bad deductions that won't get out of your head. I hope most people will still get some use out of them though, with the late arrival.

The first puzzle is a Tapa Loop. I think this is generally a pretty smooth variant and hardly ever causes real issues. This puzzle is not very difficult and if you understand how the variant works, it should go pretty quick.
The second puzzle is a Regional Tapa. The genre is a little bit restrictive in design but I had fun working with it. I did have a problem where I apparently can't count and had to change some of the regions because one region had one cell too many coloured.
The third puzzle is a Cyclic Tapa. Good for people who like classic Tapa as all deductions are like normal. Some clues just have to work for two grids instead of one. I made a stupid error in construction where I placed one pair of copied clues in different squares. But as the rules don't state they have to be in the same square I think this is still a valid puzzle. It would just look nicer. I like how it turned out. I should, it took me ages to get one out that was a bit interesting.
The fourth puzzle is a Pentapa. I always like puzzles with pentominoes, this one is no different. Certain pentominoes are more easily formed by a Tapa wall. These you can usually deduce pretty quickly and then have to try to avoid for the rest of the solve. The Tapa element still comes forward enough though and it's not just playing with pentominoes.
The fifth puzzle is a Elimination Tapa. This was the one that had the biggest error. I changed one of the digits to make a clue work, except that ruined the deductions of a lot of other clues, so had to fix that. It was luckily not the worst fix. I think it's still a nice puzzle. Good practise for bordering clues.

I hope practising all puzzles will help people in the upcoming TVC XIV. Enjoy.

Puzzles can be found below

TVC XIV Practise: Part 1

I was hoping to post these a little bit earlier, but construction of a few puzzles caused more trouble than planned. I tried to make a puzzle for all types not provided in the introduction, except I couldn't get the Cyclic Tapa to go. I tried to make it 10x10, except I might go for a smaller size to at least have something out. So instead I added a Tapa Turns to this part. The remaining five types will hopefully be out tonight or Friday morning Canberra time.

The first puzzle is a Tapa Clones. This variant allows you to only use five different clues, three of which obey this rule under normal Tapa conditions. So the influence doesn't seem to be very great, but I think it worked out okay in this puzzle.
The second puzzle is a Tapa Turns. I think it worked out pretty well. You can make the "turns" clues be very influential as the no 2x2 squares rule restricts how the clues can work.
The third puzzle is a Wordic Tapa. It's a bit of a tricky puzzle to make. The fact that 4 can be a 0 always is annoying and made the construction tricky. There were a number of times where I had to scrap a puzzle because I had missed alternate solutions where a 4 would turn into a 0 instead of 4 or 5. It could be that the actual TVC puzzle uses a different language and thus the clues don't correspond to the same digits.
The fourth puzzle is a Tapa or not Tapa. A lot of the clues end up having to be coloured. Probably possible to make a puzzle where every clue ends up getting coloured. I think it might sometimes be too easy that a clue can just get coloured as colouring wouldn't do anything to make the solution invalid, instead of having to deduce why it can't be valid. I think it worked out okay, even though I had to sacrifice symmetry for uniqueness.
The fifth puzzle is a Tapa in the Cave. The variant doesn't allow for clues over 3 and 3 clues are a bit more restrictive than normal. The variant seems pretty fun, even though I didn't particularly like the idea at the start. But that seems to more often happen with Zoltan's variant ideas. I had tried a similar idea too before, but couldn't get it out in an interesting way so never posted the puzzle. The puzzle has clue that ruins symmetry, but it was necessary for uniqueness. I couldn't add a clue symmetrically as that would be a valid clue if one was placed there.

Puzzles can be found below.

TVC XIV Practise: Introduction

Upcoming weekend will be TVC XIV on Logicmasters India. I'll be trying to write an example of each puzzle type like last year. I missed TVC XIII as I was a bit late realising it would start and had other puzzles to write at that moment. Puzzles will be posted over the next few days.
I'm using this post to direct you to some of the previous examples of some of the variants used.

Tapa Loop:
http://logicmastersindia.com/lmitests/?test=TVC13
http://logicmastersindia.com/lmitests/?test=M201207P
http://puzzleparasite.blogspot.com.au/2012/07/lmi-practise-logiraces.html
http://yureklis.wordpress.com/2012/07/22/puzzle-43-tapa-loop/

Tapa Turns:
http://anuragthefirst.blogspot.com.au/2012/09/tapa-turns.html

Tapa [Regional]:
http://mellowmelon.wordpress.com/2012/02/22/puzzle-389/
http://logicmastersindia.com/lmitests/?test=M201209P

Pentapa:
http://logicmastersindia.com/lmitests/?test=TVC7

Elimination Tapa:
http://chaosatthesky.wordpress.com/2013/05/15/deception-5/
http://logicmastersindia.com/lmitests/?test=M201305P
http://puzzleparasite.blogspot.com.au/2011/09/puzzle-11-tapa-cross-out.html

Daily League Sudoku #26: Jigsaw Killer Sudoku

This weekend a combination of two standard Sudoku variants. Although I wouldn't say it's a standard puzzle for either variant. When combining different puzzle types or variants, I think it's important to make sure they come into play together and aren't just in the puzzle together. So for this puzzle I chose a cage layout that could never work in a standard Killer Sudoku, as it could never be unique. But the Jigsaw layout allows you to use this cage layout. This puzzle also uses a tricky set of opening moves that you wouldn't normally see in a Killer Sudoku. I think this is again a harder puzzle and the opening will probably stump a few people, but it's clear logic once you find it. I promise next week I'll come with an easier puzzle. Enjoy!

Recap of the last Daily League week:
Sunday: Difference Sudoku by Seungjae Kwak
Monday: Anti-Knight Windoku by Jakub Hrazdira
Tuesday: Quadruple Sudoku by Prasanna Seshadri
Wednesday: Overlapping Diagonal Sudoku by Bastien Vial-Jaime
Thursday: Diagonally Non-Consecutive Sudoku by Rishi Puri
Friday: Classic Sudoku by Tom Collyer

Rules for Sudoku

Instead of given numbers, you now have a few dashed cages. The number in the cage indicates the sum of the digits in the cage, Digits can't be repeated in any dashed cage.

Click to enlarge

Daily League Sudoku #25: MaxiMini Sum Sudoku

I think this is also a new idea, but I can hardly know all Sudoku ideas. It's not really anything revolutionary, but I like how it worked out. I already did a similar idea before except it used maximum difference. I also added the minimum constraint here as it helped set up openings. The more frequent Daily League puzzles might get a feeling of deja-vu. This puzzle will probably again turn out on the harder side as the steps are pretty restrictive in order for the opening and it's not till the end that there's a bit more freedom on which clues to use. I've noticed that generally seems to be the deciding factor in what makes my puzzle hard or not. I hope people enjoy it though, I think it's a good solve.

Recap of the last Daily League week:
Sunday: Balanced Sudoku by Seungjae Kwak
Monday: Even Queens Sudoku by Sina Hera
Tuesday: Renban Groups Sudoku by Prasanna Seshadri
Wednesday: Killer Sudoku by Bastien Vial-Jaime
Thursday: One Way Multi-Diagonal Sudoku by Rishi Puri
Friday: Extra Regions Sudoku by Tom Collyer

Daily League PDF's:
Week 29
Week 30
Week 31

Rules for Sudoku

In this Sudoku there are clues on the outside of the grid. Numbers above or left of the grid indicate the maximum sum of two adjacent digits in that row or column. Numbers below or right of the grid indicate the minimum sum of two adjacent digits in that row or column. Each given sum appears at least once in that row or column.

World Puzzle Championship 2013: 80 puzzle around the world and blog

Here are some announcements about the 2013 World Puzzle Championship.

This year's WSC/WPC will be held from October 12th-October 19th in Beijing, China. Any additional information can be found on http://wscwpc2013.sudoku.org.cn/.

There will also be a blog with information specifically about the World Puzzle Championship hosted by the Hungarian organisation on the following link: http://wpc-2013.blogspot.hu.

Lastly, there's a new initiative tested in this year's WPC. There will be numerous outside puzzle contributing teams, each preparing a set of puzzles to solve. This round is called "Around The World in 80 Puzzles", a play on the famous Jules Verne novel. There are four contributing teams, from four different countries, each providing a set of 20 puzzles each. One of the four sets is provided by me and three other Dutch puzzle authors: Hans Eendebak, Tim Peeters and Richard Stolk. If you want to read more about it, you can on the following link: http://wpc-2013.blogspot.hu/2013/08/around-world-in-80-puzzles-introduction.html.

Daily League Sudoku #24: Greater Than Sudoku

This week a common variant again. I tend to enjoy solving these puzzles, even though design-wise there's usually not that much in them. I just like sudokus without given digits.
I've been busy writing puzzles for other purposes and then I tend to steer towards a simpler, more common variant. This type is really easy to put together. Many solutions will be unique in this type. There's a few constraints the solution should have to qualify, but it's generally just a matter of checking if it has them and then checking how it solves logically. Some have a path that's a bit too easy and others are too hard. I think this one has a nice logical path. Enjoy.


Recap of the last Daily League week:
Sunday: PS Sudoku by Seungjae Kwak
Monday: Jigsaw Sudoku by Jakub Hrazdira
Tuesday: Diagonal Compromise Sudoku by Prasanna Seshadri
Wednesday: Diagonal Sudoku by Bastien Vial-Jaime
Thursday: Non-Consecutive Sudoku by Rishi Puri
Friday: Quad Sum Sudoku by Benz Liang

Rules for Sudoku

In this Sudoku the digits have to obey all Greater than/Less than signs between cells.

Daily League Sudoku #23: Sum or Difference Sudoku

This week a Sudoku variant themed around today's date. I did it once before for Valentine's day. I somewhat stumbled into it, while just messing around with a few ideas for a Sudoku. I put down a 3 and an 8 and figured I could push it through the whole puzzle. It's split down the left bottom and right top diagonal. It's not too hard a puzzle after realising the opening. Enjoy.
The puzzle is a bit late, but I had to remake part of it as part of the logic was incorrect. Hopefully this one is without error.

Recap of the last Daily League week:
Sunday: One of Eight Sudoku by Seungjae Kwak
Monday: Pairs Sudoku by Jakub Hrazdira
Tuesday: Domino Sudoku by Prasanna Seshadri
Wednesday: Frame Sudoku by Bastien Vial-Jaime
Thursday: Odd-Even Antiknight Sudoku by Rishi Puri
Friday: Nonconsecutive Sudoku by Tom Collyer

Daily League PDF's:
Week 28

Rules for Sudoku

In this Sudoku, a number between two cells indicate either the sum of or the difference between these two cells.
[Edit: Puzzle image adjusted as one of the clues was missing]

Daily League Sudoku #22: Diagonal Sudoku

This week again something standard and easy. I don't often write classic Sudokus or standard variants. I think it is because I can't really put anything that creative in my designs for them. I can make them visually pleasing, but that is generally it. I like to put interesting logic in my puzzles, but I have trouble achieving that with normal Sudoku. That's probably because there's too many of them out there, that I feel I can't really offer anything new to the mix. Even when I try I tend to have to give up on it, because otherwise I can't get it unique. I think this one worked out okay though. I expect very fast times though from the best solvers. I don't think there are really many stumbling blocks.

Recap of the last Daily League week:

Saturday: Classic Sudoku by Tom Collyer
Sunday: Edge Product Sudoku by Seungjae Kwak
Monday: Just One Cell Samurai Sudoku by Tiit Vunk
Tuesday: Repeated Neighbours Sudoku by Prasanna Seshadri
Wednesday: Outside or Skyscraper Sudoku by Bastien Vial-Jaime
Thursday: Twin Detector Sudoku by Sina Hera
Friday: Even Sudoku by Tom Collyer

Daily League PDFs:
Week 25
Week 26
Week 27

Rules for Sudoku

In this Sudoku you also have to put the digits 1~9 once on the marked diagonals.

Daily League Sudoku #21: Hi-Lo Inner Frame Sudoku

I'm back with a Daily League Sudoku this week. I'm posting the Friday puzzle as Tom needed a bit more time and my puzzle is ready. This week I've written a combination of two nice types. The Inner Frame I first saw on the 2012 US Sudoku Qualifiers. The Hi-Lo Frame Sudoku I first encountered on the 2011 Dutch Sudoku championships.
I think they work well together. The Inner Frame idea leaves you to use some combinations that would otherwise not be possible, because there is more room for repeated digits within the different sums. I chose for an easier layout of clues that all overlap, which I think makes the solve a bit more friendly. I think it worked out well. I hope you enjoy it too.

Daily League PDFs:
Week 20
Week 21
Week 22
Week 23

As a final note, all puzzles are also solvable each day on SudokuCup. The puzzles appear a day later than in the group.

Rules for Sudoku

In this Sudoku, the numbers on the outside indicate the sum of the highest and the lowest of the three digits in the 2nd, 3rd and 4th cell seen from that side.

Puzzle #162: Pentopia

I should be in Australia by now, getting used to driving on the left, kangaroos and koalas, still not liking meat pies and trying to understand what cold means in Australia. This post is written 6 days ago though, so I might be completely wrong.

These two puzzles I have also written earlier. Checking the number of tags on my blog, it's no surprise that I would have chosen to write Yajilin and Pentopia puzzles. They're just types that come very easy to me and I always find fun to write and hope people actually like to solve. But they generally seem well received. Pentopia featured on the USPC this year, after also featuring on the WPC last year. They've also been published in Breinbrekers. So I guess that means it is getting more exposure than just my blog.
The puzzles are pretty good. The first one is a 10 clue puzzle that has a fun opening, but I couldn't get it unique with that 10th clue in a symmetrical position, so I moved one of the clues to acchieve a unique puzzle. The second puzzle has an easy opening, but takes a bit more finesse to finish.

Rules for Pentopia

Puzzle #1

Puzzle #2

Puzzle #161: Yajilin

At the point of this post I'll probably be somewhere above Asia. I'm too lazy to properly work out where my plane should be. I'm flying to Australia today. Hopefully there will be no problems and I'll get through customs there without any problems. Watching those border control shows really makes it look a bit scary. But I'm smart enough to not stock half my suitcase with food, so that should be okay, right?

The puzzles I'm posting today I made a while back, but never ended up being used where I made them for. As I now know they won't be in there, I can safely post them here. I think they worked out well. The first one was intended to symmetrical too, except I couldn't make it unique with the opening I had used. But then I noticed I could make it unique if I were to remove one of the clue squares. I think it worked out well. The second one uses some logic I don't often manage to put in these smaller Yajilin puzzles. I'm not sure if it will get noticed though. I think it works out nicely and is very reminiscent of my other Yajilins.

Rules for Yajilin

Puzzle 1

Puzzle 2

Daily League Sudoku #20: Max Difference Sudoku and Ace Sudoku

I've been a bit busier lately and didn't find the time to write out my blog posts. So I'm using this to post the two Sudokus I had posted in the Daily League page in the last 2 weeks. They were both new ideas as far as I'm aware of, but both used familiar ideas, just used in a way not done before. I think I more often go for new ideas because I don't think I can add more to common Sudoku genres as there are already so many available online.

The first puzzle iss Max Difference Sudoku. It is a variant where the maximum difference between 2 adjacent digits are marked for some rows and columns. I liked the interactions as both high and low digits can be used to force placements if you use the clues appropriately. This is actually the second puzzle as I had made a bad deduction during construction, which made the whole puzzle fall apart. I think this one actually worked out better than the way first one should have worked.

The second puzzle is an Ace Sudoku. It's a tricky variant where each 3x3 region obeys one of two rules that have been used in other puzzle, namely that either adjacent digits can't have a difference of 1 or that adjacent digits can't sum to 11. You have to deduce which of these two rules applies for each region. I always like these choice puzzles. The most common way this has been used is All Odd Or All Even Sudoku. The construction for this one took a while. I had the opening set up pretty quickly, but then spend ages trying to figure out if I could place the remaining digits in this pattern, so that it was unique. Many tries ended up without a solution as some 3x3 regions wouldn't obey either of the rules and a few ended up with multiple solution. But after a while I managed to find this puzzle. It has a few tricky steps in the middle, where you need to find the critical steps to make progress. I like how it turned out though and think it really nicely uses the rules of the genre. The name of the puzzle is derived from the Ace in Blackjack.

Rules for Sudoku

Max Difference Sudoku

In this Sudoku numbers on the outside indicate the maximum difference between two adjacent digits in that row or column. The indicated difference has to appear at least once in that row or column.

Ace Sudoku

In this Sudoku within every 3x3 region neighbouring digits either don't have a difference of 1 or don't have a sum of 11. One of these rules is true for each 3x3 region, but the other one doesn't necessary have to be false. Which of these rules is true can differ between different 3x3 regions. There are no restrictions between adjacent digits in different 3x3 regions.

Daily League Sudoku #19: Renban Sudoku

This week we again have a more familiar puzzle type, namely Renban Sudoku. It took a few tries to get this one right again. It is too easy to run into no solutions if you don't pay attention. I think it's a nice puzzle, although I generally prefer my more puzzly Sudokus, where the extra rule pushes the solve more. I think people who are more into Sudoku will enjoy these better. I think they more enjoy solving the Sudoku like deductions than trying to figure out how I managed to use a trickier rule. I doubt this Sudoku should cause too much trouble to the best solvers and is again on the easier side.

Recap of the last Daily League week:
Sunday: Greater Than Sudoku by Seungjae Kwak
Monday: Cross Number Sudoku by Benz Liang
Tuesday: Thermo Killer Sudoku by Prasanna Seshadri
Wednesday: Quad Max Sudoku by Bastien Vial-Jaime
Thursday: Anti-Knight Sudoku by Jakub Hrazdira
Friday: Classic Sudoku by Tom Collyer

Daily League PDF:
Week 19

Rules for Sudoku

In this Sudoku each area of connected grey cells must contain a set of consecutive digits. The digits don't have to be in order.

Daily League Sudoku #18: Factory Killer Sudoku

This week's puzzle is again harder. Especially the opening is tricky. It really helps to understand some of the implications. I don't think I've seen this variant before, but one can never be sure.

I've been planning on writing a Killer Sudoku variant for a while, but it never came of it. Either because other people had a Killer Sudoku or that my attempts failed and I eventually switched to another Sudoku type. This puzzle took me about 3 hours to get right. I could have made it easier, but I really liked the 2-4-6-8 grouping in the middle nonets, but that led to some uniqueness issues for a while. I wasn't sure if I could get the 2 nonet to work, but it eventually fell nicely. It's tricky, but I think it has a nice solution path. Enjoy.

Recap of the last Daily League week:

Sunday: FINDoku by Seungjae Kwak

Monday: Thermometer Sudoku by Fred Stalder

Tuesday: Outside-Consecutive Sudoku by Prasanna Seshadri

Wednesday: Argyle Sudoku by Bastien Vial-Jaime

Thursday: Even Queens Sudoku by Jakub Hrazdira

Friday: Number 5 Is Not Alive Sudoku by Tom Collyer

Rules for Sudoku

In this Sudoku there are a number of dashes cages. A number in a dashed cage indicates a factor of the sum of the digits in its cage. Digits can't repeat within a cage.

Daily League Sudoku #17: Anti-Knight Sudoku

I didn't have very much inspiration this week to create a Sudoku, so I stepped back to a familiar type. I generally like Anti-Knight Sudokus. This one I constructed with a computer program as backup, to make sure that the there were still valid solutions. This means that when I can't find a valid solution, I check which of the givens I placed led to a situation where there no longer is a valid solution. This saves me from having to backtrack a lot as it can happen that you place multiple givens without being able to see that there is no longer a valid solution. I think the puzzle turned out nice. Enjoy.

Recap of the last Daily League week:

Sunday: Roman Non-Consecutive Sudoku by Seungjae Kwak

Monday: Extra Regions Sudoku by Fred Stalder

Tuesday: Arrow Sudoku by Prasanna Seshadri

Wednesday: Diamond Sudoku by Bastien Vial-Jaime

Thursday: No 3 Skyscraper Sudoku by Jan Zverina

Friday: Nonconsecutive Sudoku by Tom Collyer

Daily League PDF:

Week 18

Rules for Sudoku

In this Sudoku, two cells that are a Knights move away from eachother are always different.

Daily League Sudoku #16: Jigsaw Sudoku

This week no complicated rules but just a Jigsaw Sudoku. I like writing Jigsaw Sudokus. I always try to get the total clue count to 16 or less. I tend to draw out the cage patterns and not all Law of Leftover areas before starting so I can use it when needed. I feel it always helps the design along when you keep good track of that. I don't think the puzzle has anything special, but it's still fun to solve.

Recap of the last week.
Sunday: Clock Faces Sudoku by Seungjae Kwak
Monday: Sequence Sudoku by Fred Stalder
Tuesday: All Even or All Odd Sudoku by Prasanna Seshadri
Wednesday: Diagonal Sudoku by Bastien Vial-Jaime
Thursday: Odd Even Stars Sudoku by Jakub Hrazdira
Friday: Extra Regions Sudoku by Tom Collyer

Daily League PDF's:
Week 16
Week 17

Rules for Sudoku

Daily League Sudoku #15: Difference Sudoku

This week I made a Difference Sudoku. I know I've made a lot of arithmetics-based variants. I think it's just what I'm most comfortable with. Just like I am most comfortable writing Loop genres when making puzzles.
I don't think this puzzle should be too hard. After last week an easier puzzle is probably appreciated. This puzzle has a simple opening and gets a bit harder in the middle, but nothing that should really break up the best solvers. Enjoy.

Recap of the last week:
Sunday: 2-Frame Sudoku by Seungjae Kwak
Monday: Arrow Skyscrapers Sudoku by Fred Stalder
Tuesday: Odd Sudoku with Descriptive Pairs by Prasanna Seshadri
Wednesday: Even Consecutive Sudokube by Bastien Vial-Jaime
Thursday: Odd Even Killer Sudoku by Christoph Seeliger
Friday: Jigsaw Sudoku by Jakub Hrazdira

Rules for Sudoku

In this Sudoku, numbers between two cells indicate the difference between the digits in those 2 cells.

Daily League Sudoku #14: Odd Even Frame Sudoku

Last week I didn't contribute a Sudoku to the Daily League, but this week I'm back. This week features another Frame Sudoku variant. As I'm a fan of most sudokus with sums and I'm pretty good at them, writing these generally comes pretty easy to me. It generally avoids the annoying problem of running out of solutions. I'm pretty sure I've seen this variant before. I'm just not able to remember where I have.
The last few Sudokus had been a bit easier than some of my others. I think this one will again be a bit more challenging, because it has a bit narrower solution path. I think I used the rules pretty well and it stays challenging till the end. I don't want to scare anyone off. I don't think there are any really hard deductions. I just expect slower times than in the previous few weeks. I hope you all enjoy it.

Recap of the last 2 weeks:

Sunday: Coded Sudoku by Seungjae Kwak
Monday: Odd Antiknight Sudoku by Jan Zverina
Tuesday: Anti-Diagonal and Fortress Sudoku by Prasanna Seshadri
Wednesday: Greater Than Sudoku by Bastien Vial-Jaime
Thursday: No Donkey Step Sudoku by Rishi Puri
Friday: Unique Sums Sudoku by Jakub Hrazdira
Saturday: Equal Sudoku by Christoph Seeliger

Sunday: Extra Regions Sudoku by Seungjae Kwak
Monday: Irregular Scattered Sudoku by Fred Stalder
Tuesday: Kropki Sudoku by Prasanna Seshadri
Wednesday: Figures Sudoku by Bastien Vial-Jaime
Thursday: Asterisk Sudoku by Rishi Puri
Friday: Frameless Sudoku by Jakub Hrazdira

Daily League PDF's:
Week 14
Week 15

Rules for Sudoku

In this Sudoku, the numbers on the outside indicate the sum of all odd digits or the sum of all even digits in the first 3 cells seen from that side. It can be that a clue indicates both the sum of all odd digits and the sum of all even digits.

Puzzle #160: Fillomino

This puzzle was written as a birthday present to Zuzana Hromcova. Matus Demiger contacted numerous authors to make a puzzle for her birthday to create a set of 18 puzzles for her 18th birthday. This is my puzzle. It's a standard Fillomino. I think the theming should be clear to everyone. The red numbers have no special meaning for the solve, but you can probably figure out why they are red. I really like how the solve turned out. I hope Zuzana enjoyed it.

Rules for Fillomino

Click to enlarge

Daily League Sudoku #13: Consecutive Clone Sudoku

Another week, another Sudoku. This week a small twist on the Clone Sudoku genre. Normally the Clone Sudoku has the same digits in the same places for equal shapes. For this one the digits are consecutive in the same places instead. I think it makes the solve a bit trickier than normal. It definitely made the construction a bit more confusing. It took me a few tries to get a puzzles out with valid solutions, after which a few of those ended up not being unique because I had eliminated digits I shouldn't have.
I find designing Sudokus like these harder in general. I'm usually better with a more influential rule, which I can then exploit. That's why I generally prefer designing Sudokus that require no or only little givens in the grid. That's why in these types of Sudokus, I usually give it many tries, till I get a puzzle I'm happy with. I tend to be a bit picky about my puzzles and often rewrite and edit already nice puzzles, because a part of it doesn't come out the way I had planned to. So I change them to highlight it. In this one I had started with two extra cloned shapes, but then I thought it would be nicer to just have the same shapes for givens as Cloned areas. The second try ended up with one extra digit in the center. I liked it and it solved nicely. But still I really wanted that middle digit gone too, so I gave it another go. And eventually this was the result. This solves nicely and is in my opinion the nicest of the three. It shouldn't be too hard, but of course there's always the challenge of adapting to a new rule set. My Quad Second Sudoku had some people struggling to overcome not solving it as a Quad Max, so here people might get stuck looking at it as a regular Clone Sudoku. So try not to do that. Enjoy.

For anyone interested, you are still free to join the Daily League Group or you can request access to the Google Spreadsheet from Rishi Puri. You can also solve all puzzles the day after at SudokuCup.

Recap of the last week:
Sunday: Non-Consecutive Sudoku by Seungjae Kwak
Monday: Double Extra Regions Sudoku by Fred Stalder
Tuesday: Outside or Skyscraper Sudoku by Prasanna Seshadri
Wednesday: 2 Even 2 Odd Sudoku by Bastien Vial-Jaime
Thursday: Killer Sudoku by Rishi Puri
Friday: Palindrome Sudoku by Tom Collyer

Daily League PDF:
Week 13

Lastly, if anyone is interested in contributing for the Daily League, now is the perfect time. Many of our regular authors are busy with their National Championships and other obligations. So anyone interested in jumping in and writing a Sudoku for the Daily League, give it a try.

Rules for Sudoku

In this Sudoku, digits in the same place in both grey figures have to be consecutive.

Daily League Sudoku #12: Frameless Sudoku

This week again one of my own ideas for the Daily League. I have posted a few of these already on my blog. I came up with this type as a response to the repetetiveness of Frame Sudokus. I always enjoyed solving Frame Sudokus, but after a while they get a bit the same. This rule set adds to the diversity of the solve as you now have more ways of creating openings and keeping the solving path narrower.
This puzzle is easier than the other Frameless Sudokus I have made, to make it more suitable for speedsolving. The path is solving path is still narrow, but you get a few easy digits to start off with. I think the equal sums on the left and right side are a nice touch. I was planning on making two sequences at the top and bottom too. Except the 16 and 18 clues wouldn't work in order with the other clues, but did work switched. So I figured that would be good enough. This puzzle can also be used as practise for the upcoming Serbian Round of the WPF Sudoku Gran Prix held from April 20th-April22nd, which features a Frameless Sudoku.

Recap of the last week:
Sunday: Prime Number Sudoku by Seungjae Kwak
Monday: Untouch diagonal Sudoku by Fred Stalder
Tuesday: XV Sudoku by Prasanna Seshadri
Wednesday: Sudokurve by Bastien Vial-Jaime
Thursday: Non-Consecutive Sudoku by Rishi Puri
Friday: Classic Sudoku by Tom Collyer

Daily League PDF:
Week 12

Rules for Sudoku

The numbers on the outside indicate the sum of the first digits encountered in that row or column from that side. The amount of digits can differ from sum to sum and can be only one digit.

Daily League Sudoku #11: Windoku

This week a Windoku. It will probably be one of the easiest puzzles I have made for the league. I like Windoku puzzles. I always prefer the puzzles that don't have any clues in the 4 extra windows. I had actually written this puzzle a while back, but I haven't used or posted it anywhere. As I like how it looks and solves, I'm using it for the league. I hope you enjoy it too.

Recap of last week:
Sunday's Little Addition or Multiplication Killer Sudoku by Seungjae Kwak
Monday's Knightly Non-Consecutive Sudoku by Fred Stalder
Tuesday's Disjoint Groups Sudoku by Prasanna Seshadri
Wednesday's Extra Regions with Mirrored Cells Sudoku by Bastien Vial-Jaime
Thursday's Diagonally Non-Consecutive Sudoku by Rishi Puri
Friday's Classic Sudoku by Tom Collyer

Sudoku Pdf:
Week 11

Rules for Sudoku

In this Sudoku, you also have to place digits 1~9 once in every grey 3x3 square.

Daily League Sudoku #10: Average Sudoku

Another week, another Sudoku. This week an Average Sudoku. I like the idea. It's similar to Arrow Sudoku, except the digit is the average instead of the sum of the digits. I think enough can be done with it. I'm not sure if this idea has been done before, but I can't imagine it hasn't been. But I have that idea with any Sudoku Variant I come up with as there are already so many out there. But people constantly come up with new variants.
This Sudoku shouldn't be too hard. It has, like most my variants, a pretty narrow opening. But I think it should be clear where it lies this time. If you understand the basics of this variant it should go pretty smoothly. There's no real difficult steps in this puzzle, but you just have to go through them in the right order. I'm hoping this will have a bit faster times than my previous ones though. But I'm never sure how they'll turn out.

A recap of the last week's Daily Sudokus: Sunday's Outside Sudoku by Seungjae Kwak, Monday's Sum or Product Frame Sudoku by Min Young Yoo, Tuesday's Consecutive Sudoku by Prasanna Seshadri, Wednesday's Irregular Sudoku by Bastien Vial-Jaime, Thursday's Palindrome Sudoku by Rishi Puri, Friday's Tens Sudoku by Tom Collyer.

Daily League PDF file:
Week 10

Rules for Sudoku

In this Sudoku a digit in a circle is the average of the digits in all cells connected to it with a line.

Click to enlarge

Daily League Sudoku #9: Kid Sudoku

This week's Sudoku is a Kid Sudoku. When I first saw the idea, I just thought it was a funny idea. I don't remember where I first saw it though. I tried googling for other examples, but that proved to be unsuccesful. Apparently there are A LOT of websites with Sudokus for kids. I'm generally a fan of Sudokus with summed clues, so this was right up my alley for design. I wrote this puzzle in an hour long train ride back home. The opening was set up pretty quickly. I had an idea, it worked and as this type only clues in one direction, I knew I could always make the rest of the puzzle work. The center 99999 clue was something I wanted to keep in and in continuing the design it worked nicely with the clues. Finishing the puzzle took me a few tries so that there were no obvious new openings. I'm not sure how hard this puzzle is, but I suspect it to again be on the harder side. Hope everyone still enjoys it though.

A recap of the last Daily Week: Sunday's Rossini with Disjoint Groups Sudoku by Seungjae Kwak Monday's Irregular Sudoku by Fred Stalder, Tuesday's Weighted Killer by Prasanna Seshadri, Wednesday's Thermo Sudoku by Bastien Vial-Jaime, Thursday's Even/Odd Skayscraper Sudoku by Rishi Puri, Friday's Twodoku by Tom Collyer.

Pdf files of the last 2 weeks:
Week 8
Week 9

Rules for Sudoku

The clues on the outside are given by a kid that can't count past 9. He adds up all digits in each row from left to right. Every time the sum would go over 9 he restarts. So for example the clue for the row 154638279 would be 649899.

Click to enlarge

UK Puzzle Championship 2013

Today my puzzles for the UK puzzle championships. The UK Puzzle and Sudoku championships were held last weekend. Tom Collyer won the UK Sudoku championship and Neil Zussman won the UK Puzzle championship. My puzzles were the last individual round of the championship. It featured a relay, with 9 puzzles that have to be solved in order. Each puzzle solution would in some way transfer to the next, so that this puzzle would become solvable. I will be posting all puzzles and relay tags below, but to see how everything works, you can check the instruction booklet for this round here.

The original idea for this round came from the 2003 WPC in Arnhem. I have made a round like this before for another online competition. I used similar relays in that round as well. As that round wasn't done on time, I wasn't sure how many of these relays would work on time. Some relays are good without time, but things like copying the shapes of a Fillomino solution are very annoying in my mind for a speed contest.
The first puzzles I wrote were the Snake and Nurikabe puzzles, as I had used the Snake to Nurikabe relay before and liked it. I wrote a Snake puzzle with few clues, so that I could easily write a puzzle that had these clues inside the grid, which could then be transferred to the side. I then opted writing a Kakuro puzzle as the opening puzzle, as most solvers are familiar with that. With this the first 3 puzzles were all types that most people in the puzzling community have done multiple of. The next part of the design was getting from Nurikabe somehow back to number clues. I then found the combination Yin Yang/Hiroimono, which I thought was a nice transition, with a few less familiar puzzles. I did have to figure out how to properly write Hiroimono puzzles without any given clues as I had never done that before. From here I opted to write a Doppelblock puzzle. It was easiest to write this puzzle without any repeating clues as this would make the relay the smoothest. It was a bit hard to get it right, as some clues are just more conductive in this puzzle type. I was planning on writing a Minesweeper puzzle next, and figured I could easily relay it to any puzzle type. That's why I chose to write a Magnets next, which could transfer to a Battleships puzzle. I wrote a Magnets puzzle with missing clues, which I have written many of. I chose a smaller size as they are generally viewed as hard to many people. I had to make sure the remaining clues were under 20 as that's the max number of ship segments a standard Battleships puzzle has. It worked out perfectly and the Battleships construction was really easy to finish. When I went back, I couldn't get the Minesweeper in a way that the relay to it and from it was nice. That's why I tried a number of other puzzle types. Then I tried Country Road, which caused an odd design experience. I tried to write them normally, except I couldn't get it so it would transfer to the already written Magnets puzzle, so that's why I changed it around. I first marked a bunch of empty squares so that it would transfer properly to the Magnets puzzle, and then reversely engineered the regions so a solvable valid puzzle would exist which has those empty squares in those places. I think the result is nice and I doubt anyone would expect it was designed that way from the solve. I thought 9 puzzles would be enough, even though I had originally planned on making 10 puzzles. I just think some of the relays would take more time than others, so I thought this would make a long enough round for the championship.

The puzzles can be found below.

Polish Puzzle Championships 2013

This week is a week full of puzzles on my blog. That is because the last two weekends there were two championships to which I contributed puzzles. Today I will post all puzzles from the Polish Puzzle Championship and Thursday will feature my puzzles for the UK Puzzle Championship.

The Polish Sudoku and Puzzle Championships were held in the weekend of 9 and 10 of March. Jan Mrozowski became the Polish Sudoku Champion. Przemysław Dębiak won the Polish Puzzle Championship. The puzzles for the Polish Sudoku Championship can be found here; the puzzles for thePolish Puzzle Championship can be found here. My puzzles were round 5 of the Puzzle championship. I also found a video of the Polish Puzzle Championship on Serkan Yurekli's blog. In the beginning you can see puzzlers working on my puzzle set. The end is the finals.

For the Polish Championship I employed a copycat theme. The puzzles came in pairs and each pair of puzzles had a similarity in the layout. Most of these types are very closely related in the puzzle type. The only pair that really isn't very close to the other were the Star Battle and Heyawake. I was happy to see that the puzzles were printed on bordering pages in the puzzle booklet, so solvers might notice the similarity.
The idea somewhat accidentally happened. I had made an easy Akari puzzle and wanted to make a harder regional Akari and opted to make one with the same black squares. When I finished those I wondered if I could keep doing that and went with a Liar Loop/Maxi Loop combo as that seemed most easily acchieved. And I'm pretty comfortable designing those, so made two with the same regions. The next puzzles I made were the Capsules and Ripple Effect puzzles, I posted earlier which ended up testing too hard. I really like constructing Ripple Effect puzzles, but clearly not that skilled at making them competition difficulty. I looked through my Double Trouble collection and thought Turning Fences and Slitherlink should be easily made look similar. I chose the same clue positions and about half the clues are the same. I already had 4 Loop puzzles, so that was all of those I could put in. I made a Tapa and Nurikabe with the same clue positions. I at first tried to also make the Nurikabe clues to be the sum of the Tapa clues, but that didn't prove to be very fruitful. I then started doodling a bit and made a Small Regions Star Battle and wondered what type I could use these cages for. I eventually settled on Heyawake as that would allow me to add some clues and see where it goes. The regions were still very restrictive on the Heyawake genre, but managed to push it out with just 2013 as clues. Lastly I needed some Magic Square genres. I thought first about doing Skyscraper/Haido, but figured with multiple similar types, maybe I should try a more different type. So I made a Skyscraper puzzle, to which I added a number of clues to turn it into an Easy as Japanese Sums puzzle. I felt I was somewhat missing a division type puzzle, but I couldn't find a nice way to make 2 that fit into the theme. And when I had the puzzles tested it seemed like there was enough to fill the hour slot already.

I also wrote a LITS puzzle to be used for the finals, except that one wasn't used. It willbe posted at the end of this post.

Puzzles can be found below.

Daily League Sudoku #8: Sum Sandwich Sudoku

Next week will be Richard Stolk's third LMI Sudoku test. The test is named V2V or Variations to Variations. It features 14 Sudoku puzzles, which consist of 7 Sudoku Variants and a variation of each. This week's Sudoku will be one of the V2V puzzle types.

I've chosen Sum Sandwich Sudoku as this week's puzzle type. I was debating between Rank Killer Sudoku and Sum Sandwich Sudoku, but I feel I generally design better Sudokus with outside clues. That's why I chose Sum Sandwich Sudoku. My first thought was to see if I could make one without any inside clues. But to set that up I was doing a lot of analysis of the interaction between clues, which I figure was making it a bit too hard. So I figured I'd probably better just make a more solvable Sudoku. So I set up the nice diagonal line of clues and started with the design. It still turned out a bit on the harder side, even though the all numbers are given did lead to a few unintended outside clues. But they don't ruin the opening, so I'm happy with the result. Enjoy.

It is now also possible to solve the Daily League puzzles on SudokuCup. The puzzles will appear there one day after they appear in the group and on the respective blogs.

A recap of the last week of the Daily League: Seungjae Kwak's Odd Sudoku, Fred Stalder's Diagonally Non-Consecutive Sudoku, Prasanna Seshadri's Galloping Horses Sudoku, Bastien Vial-Jaime's Figures Sudoku, Rishi Puri's Anti-Knight Sudoku and Tom Collyer's Diagonal Sudoku.

Rules for Sudoku

In this Sudoku for each row and column all digits are given that are sandwiched by two digits whose sum is equal to itself.

Click to enlarge

Daily League Sudoku #7: Ten Box Sudoku

I know there haven't been many puzzles from me lately, but my puzzle creating has been directed at other projects. A number of Puzzle Championships are coming up to which I contributed and I'm also working on contributing to Thomas Snyder's puzzle project. This all means there will be that eventually I will be posting a lot of puzzles after this is all over.

I'm still finding some time to make a Sudoku each week as that is a welcome break from making puzzles. For me in general designing a Sudoku just feels a bit different than designing any other puzzle. Although my puzzle mind still drives itself through in my Sudoku sometimes. This leads to me putting some more puzzly deductions in a Sudoku that I find very simple. For last week's Sudoku this was oriented around R5C5. I thought the deduction for that cell was pretty obvious, except I think that deduction got a lot of people very stuck and led to much slower times than I had expected.

This week I made a Ten Box Sudoku, which is a nice variation of the Toroidal Sudoku. I remember this variant from the WSC 2010. I liked that puzzle. It was also in the round I did best in. I still have a certificate from that round, showing that I was the best puzzler not in the top 10 in that round. It's not that hard a puzzle, but the variant has some tricks that really suit me so I'm reserving judgement on the actual times of the league's competitors.

In the last week we've seen the following Sudokus: Seungjae Kwak's Magic Summer Sudoku, Fred Stalder's Arrow Sudoku, Prasanna Seshadri's Search 9 Sudoku, Bastien Vial-Jaime's Renban Groups Sudoku, Rishi Puri's Even Odd Chessdoku, Tom Collyer's Number 8 Still Alive Sudoku.

Lastly, the PDF of week 7.

Rules for Sudoku

This Sudoku is made up of 10 rows, 10 columns and 10 3x3 boxes. Some of the boxes wrap around the edges of the grid.

Click to enlarge

Daily League Sudoku #6: Quad Second Sudoku

First off, yesterday the Puzzle Marathon on Logicmasters India started. It is a puzzle test which features 12 large puzzles by 12different authors. The contest will run from March 1st-March 10th. You can solve each puzzle seperately over the course of the week. This test features a Maxi Loop puzzle by me. Everyone should try to compete as there will definitely be some very nice puzzles. Even if you can only manage to solve a few of the puzzles, it should be worth the time.

Now back to this week's Daily League Sudoku. The last week has featured a nice Multiplication Table Sudoku by Seungjae Kwak, an easy Killer Pair Sudoku by Fred Stalder, a challenging but fun Point to the Next Sudoku by Prasanna Seshadri, a very hard Greater than Killer by Bastien Vial-Jaime, a Non-Consecutive Anti-Knight Sudoku by Rishi Puri and a Classic Sudoku by Tom Collyer.

This time I've made a Quad Second Sudoku, which is a twist on the Quad Max Sudoku. As far as I know it's an original variant. I think it changes the solve of a Quad Max enough to make for a fun new variant. For me personally this is my favourite puzzle I have made for the League so far. I think I got the right difficulty with this puzzle compared to some of my earlier puzzles. Hope enjoy it.

Lastly, here are the link to the PDF of Week 6.

Rules for Sudoku

In this Sudoku an arrow points at the second highest digit in the four cells around it. Digits may repeat around an arrow, but the second highest digit is always unique.

Click to enlarge

Daily League Sudoku #5: Scattered Sudoku

This is my fifth Sudoku for the Daily Sudoku League. The last week so far has featured a Counting on Line Sudoku by Seungjae Kwak, an Equal Sudoku by Christoph Seeliger, a Between 1and 9 Sudoku by Prasanna Seshadri, a Fortress Sudoku by Bastien Vial-Jaime, a Little Killer by Rishi Puri and an Odd Sudoku by Tom Collyer.
This week I've gone for a simpler and more familiar variant. Scattered Sudoku is just a Jigsaw Sudoku with one non-contiguous region. The puzzle has only 17 clues, which is what I like about Jigsaw Sudokus. I like to get the amount of clues down to 20 or less, which is something I wouldn't get done in Classic Sudokus. The solve gets a bit trickier towards the end, but nothing overly difficult. It's in my opinion easier than the last two Sudokus I have posted. Hope you all enjoy them

Lastly, here is the latest PDF-file.
Week 5

Rules for Sudoku


This Sudoku has one non-contiguous 9 cell region, marked by the grey cells.

Puzzle #159: Capsules

This is a simple puzzle idea that can leave for really tricky puzzles. Most puzzles use similar techniques, except the way you employ them can make a puzzle far trickier. The grid size is a bit limited as the total number of cells has to be divisable by 5. But you can easily change certain sizes in nice ways to valid size. Leave out the center cell in a 9x9 grid, or the four corner squares in a 7x7 or 8x8 grid.
The last puzzle I post here was meant for a puzzle championship, but tested too hard, just like Tuesday's Ripple Effect puzzle. As this would be the first one I posted here, I added two extra smaller puzzles just to prepare people for the harder logic in the last puzzle. Both these smaller puzzles use a key part of the solving logic for the larger puzzle. Hopefully they help and you will enjoy all puzzles.

Rules for Capsules

Puzzle #1

 Puzzle #2

Puzzle #3

Rules: Capsules

Place the digits 1~5 once in every blackbordered region. No two equal digits can touch eachother, not even diagonally.

Puzzle #158: Ripple Effect

This is a puzzle originally intended for a puzzle competition, but testing came up with too high times so I'm posting it here now. I know it's different from my normal clueless ones, but there's a reason they were there. You might be able to figure out why later in the week. I think it still solves really nicely and has its tricky spots. A lot of the solve is very similar to my previous puzzles andthere is still a very directed path to the puzzle. I think I will always have trouble writing Ripple Effect puzzles that are more suitable for competition as there is a lot of fun logic to exploit, which is pretty tricky. I could of course put in far more smaller cages, except that is really not very fun to write for me. Anyways, enjoy the puzzle.

Rules for Ripple Effect

Daily League Sudoku #4: V-Day Sudoku

This week was Valentine's Day, which has influenced a lot of puzzles this week.
My Sudoku is inspired by the abbreviation for Valentine's Day, which seems to be used more often these days, namely V-Day. That's why my Sudoku is themed around the number 5 or V in Roman numerals. It's basically a simple variation of XV Sudoku, except I changed the X pairing of a sum of 10 to a pairing of a difference of 5. The only real difference in the solve is that you don't know whether a mark is a sum of 5 or a difference of 5. As a further theme, the givens spell out the date of Valentine's day: 14-2. For Americans who feel the date is written wrong, you could rotate the grid 180 degrees and spell out 2-14 in the same squares that are filled now and still solve it in the same way. The switching of the places for 1 and 4 doesn't matter and keeps the puzzle unique, but the solution does change a bit.
The puzzle is moderately difficult. Not too difficult, but you have to remember well that all hearts are given.

Rules for Sudoku

Everywhere two adjacent digits have a sum or a difference of 5 a heart is given.