Saturday 31 August 2013

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.

Friday 30 August 2013

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

Thursday 29 August 2013

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.

Saturday 24 August 2013

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

Saturday 17 August 2013

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.

Monday 12 August 2013

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

There will also be a blog with information specifically about the World Puzzle Championship hosted by the Hungarian organisation on the following link:

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:

Saturday 10 August 2013

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.

Saturday 3 August 2013

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]