Sunday 31 January 2016

UKPA Open: Introduction

I wrote a set of puzzles for the UKPA Open 2016 held at Selsdon Park Hotel in Croydon this year. The championship will be held the 27th and 28th of February. The Sudoku tournament will be held on the 27th of February. The Puzzle Championship will be held in two sessions over the 27th and 28th of February. The championship is open to foreign competitors.

While writing this set, I wrote two puzzles per type and selected one to be included in the final set. I will be releasing all puzzles that were not included in the set as preparation. Most of these puzzles will be a bit harder than the actual puzzles in the set, but I figure any example is better than nothing. The puzzles will be posted from Monday through Thursday for the next four weeks.

The set I wrote was based around the numbers 2, 3, 4 and 5. It started when I was playing around with different types to include in the set. I was thinking of including Norinori, which uses dominos, as I'd never written one. Then I thought Trio Cut, which uses triominos, might be fun too. Then I thought there are also similar types that use tetrominos and pentominos too.
So I tried to find more types that are somewhat similar that use the same polyominos. Three groups I had quickly put together. The number place category was a bit harder. I couldn't really remember any types that use triominos or tetrominos to place symbols in. So I changed that group a little to types that use 1~2, 1~3, 1~4 and 1~5 instead as that was easier to establish.

I hope these puzzles are useful and the set enjoyable.

The eventual groups and types that were used are as follows.

Room Placement:

- Norinori
- Trio Cut
- Tetromino Areas
- Pentomino In A Box

These are all types that place polyominos by using rooms.

Split Wall:

- Domino Nurikabe
- Triomino Tapa
- Filled Loop

These are all types where you create a wall (or loop) that needs to be split into polyominos.


- Dominos
- Sandwich
- L-Division
- Pentominous

These are all types where the grid has to be divided into polyominos of the same size.

Number Placement:

- Sum Sweeper
- Neighbours
- Magic Snail
- Capsules

These types use an increasing set of numbers.

Daily League #58: Odd's Neighbours Sum Sudoku

This is the last Sudoku in the Odd Sudoku series. This variant revisits last week's variant. This time the clues outside indicate the sum of the neighbours of the second odd digit. I thought that might make for an interesting variant.

This puzzle was harder to construct than last week's puzzle as you're giving less information about the neighbours. Finding a good opening wasn't all that easy, but this one works well. The whole design was a careful process. I ran in a few problems where there no longer was any valid solution left. The puzzle has a very narrow logical path, but I like how it all worked out. Don't expect this to be a fast solve, but it should still be fun. Enjoy.

Rules for Sudoku

In this Sudoku the numbers on the outside indicate the sum of the neighbouring digits of the second odd digit in that row or column, when looking from that side.

Click to enlarge

Sunday 24 January 2016

Daily League #57: Odd's Neighbours Sudoku

This is the fourth Sudoku in the Odd Sudoku series. It's a new variant called Odd's Neighbours Sudoku. It is similar to Next To Nine Sudoku. In this Sudoku, digits on the outside are the digits next to the second odd digit in that row or column. The second odd digit works the nicest in my mind, as the first odd digit has five single digit clues per side. I played around with a lot of similar ideas like this, but this was the one I thought worked the nicest. I actually think there's a lot of different things happening in this genre and it's one of my favourite variants I came up with.

It was a bit of trouble thinking of a nice opening, but I think this way works well. I figured out a few different openings, but this was the first I came up with. At the start I thought I would need a lot of clues to get this puzzle to work. But as I got through the opening I noticed I would need a lot less clues than I had at first imagined. I liked how the neighbouring digits worked together with the second odd digit rule. I think this was my favourite puzzle to design in the series.  I hope you enjoy it too.

Rules for Sudoku

In this Sudoku digits on the outside indicate the direct neighbours off the second odd digit in that row or column, when looking from that side.

Click to enlarge

Sunday 17 January 2016

Daily League #56: Odd Arrow Sudoku

This is the third Sudoku in the Odd Sudoku series. It is called Odd Arrow Sudoku. I haven't seen this variant before. It is a simple variant of Arrow Sudoku. In this puzzle the digit in the circle indicates the amount of odd digits along its arrow.

When first starting the design, I wasn't sure how to create a nice opening. I knew I had to have longer arrows to create an interesting puzzle as otherwise the possibilities in the circle would be too limited. After choosing this layout, I had a bit of trouble creating an opening. After a few tries, I had a nice opening. It wouldn't really become unique though. I could fix it with extra givens, but I'd rather not. When I added the arrow in the centre nonet, it allowed me to remove some givens to rework the end of the puzzle a bit. In the end this was the result and I think it's a nice solve. Enjoy.

Rules for Sudoku

In this Sudoku, a digit in a circle indicates the number of odd digits along its arrow.

Click to enlarge

Friday 15 January 2016

TVC XVIII Practise: Part 2

This is the second part of the TVC XVIII practise set. This took a bit longer to prepare. Certain puzzles didn't want to become unique. Especially the Different Tapa took a while to construct. I think the average difficulty of this bunch is a bit higher that the previous part. This is partly because it contains more new genres, so it will take a bit of discovering the new knowledge in the variants.

The first puzzle is a Different Tapa. I took a bit of time to find a nice workable layout that didn't use the same shapes as the WPC puzzle and Robert Volmert's puzzle. I think layout looks nice and gave me enough room to place clues, while the shapes do interact. It took me a while to write this puzzle as I couldn't find a way to make it both unique and having a solution. In the end I managed to move 2 clues around, which finally made it unique. It's a tricky puzzle and you'll need to use the shape from early on in the solve to make progress.
The second puzzle is a Dissected Tapa. These are never too hard. Yin Yang is a good genre to practise for these puzzles.
The third puzzle is a Not Alone Tapa. I'm not sure about this genre. It seems very limiting as this 5 clue puzzle will show. For example, you can't have any T-shapes in the wall unless it's next to a clue cell.
The fourth puzzle is a Black Hole Tapa. I like the change that was made from the original instructions in the booklet. Having the count for the black hole and the amount of black holes both be variables can lead to completely different puzzle. I went for three black holes of value 2, which I think worked out well.
The last puzzle is a 4x4 Tapa. This puzzle somehow worked out this way with only 2 clues per 10x10 grid. There's a lot of things you need to take into account with this genre and I think this puzzle will help teach most of those things. It's important to think of the global picture to understand which deductions to make.

I hope all of this is helpful. Enjoy.

[Edit: wrong clue in Black Hole Tapa fixed]

Puzzles can be found below.

Thursday 14 January 2016

TVC XVIII Practise: Part 1

Here is part one of the TVC XVIII practise. It features five different variants. The second part will come out later tonight or tomorrow, depending on how much time I can find the rest of the day.

This post will contain the first five types in the instruction booklet. I managed to get through them in a nice way in order for once. Usually one type gives me some trouble.
First there is a Tapa With Borders. I decided to go for a 7x7 grid this time. I tried to avoid any wrong clues in the centre 4x4 square, so you couldn't directly work from there to find the grid.
The second puzzle is a Tapa-Like Loop. It's not really a Tapa, but it's a fun genre. The puzzle shouldn't be too hard.
The third puzzle is a Tapa LITS. This puzzle caused me the most trouble to make. I liked the layout, but it took some time to get a valid solution. Often I had areas that just wouldn't split up into tetrominos or it just wouldn't be unique. Eventually this came out.
Tapa Scrabble. I'm not much a fan of this type. Word puzzles are generally not my type anyway. I hope this puzzle is somewhat representative for the competition puzzles. I have the most doubt about this type.
Tapa Connection. This is probably the hardest puzzle in this set. This type is really restrictive. I wanted to see how far I could push it. Four clues with three pairs of letters gets you pretty close to the minimum I think for this size.

I hope the puzzles are useful. Enjoy.

Puzzles can be found below.

TVC XVIII Practise: Introduction

TVC XVIII is on this weekend. It will feature ten Tapa variants, five of which have not appeared in the TVC previously. These variants are Tapa LITS, Different Tapa, Not Alone Tapa, Black Hole Tapa and 4x4 Tapa.

Some examples of these new variants can be found online.

Tapa LITS:
Grandmaster Puzzles
A Cleverly Titled Logic Puzzle Blog (Streampunk/Tetra Firma)

Different Tapa:
Maybe Puzzles

This post will also contain some examples of the known variants that have featured on this blog below.

Sunday 10 January 2016

Puzzle #172: Tapa; Circled

This is the last of three posts with new Tapa variants for the TVC.

The last variant is Circled Tapa. It is based on Black and White Snake. As there is already a Black and White Tapa, I couldn't go with that name. My second thought was Dotted Tapa, but then I remembered Prasanna's Dotted Tapas. So lastly I settled on Circled Tapa, by just changing the wording of the rules. The variant here is that the Tapa wall is built up of alternating black and white circles. The clues indicate how many circles of a particular colour there are around it, instead of the number of coloured cells.

In this Tapa the wall is made up of alternating black and white circles. There are black and white clue cells. White clue cells indicate the amount of white circles in the orthogonally connected sections of the wall around that cell. Black clue cells indicate the amount of black circles in the orthogonally connected sections of the wall around that cell. Each digit indicates a section of at least length 1.

Click to enlarge

Daily League #55: Odd Labyrinth Sudoku

The second puzzle in the Odd Sudoku series is an Odd Labyrinth Sudoku. I always enjoy solving these puzzles. It has a bit of puzzling in them, which always suits me well. You also get to create an odd/even grid, which is something I always enjoy. Parity variants always seem to suit me well.

In the design I tried to find some interesting deductions in this genre. If that totally worked, I'm not sure, but I had fun designing it. I didn't bother resolving any old puzzles, so it could be that this has been used before. It took a while to construct a valid puzzle though, as too often some of my logic led to no path existing. I think I lost some of the interesting things because I also had to make it unique, but it should still be a fun solve.

Rules for Sudoku

In this Sudoku there has to be a path that runs from the left top corner to the right bottom corner over cells that contain odd digits. This path can only travel horizontally and vertically.

Click to enlarge

Saturday 9 January 2016

Puzzle #171: Tapa; Castle

This is the second post of three new Tapa variants for the currently ongoing TVC.

This time the variant is Castle Tapa. This variant is based on the Castle Wall genre, hence the name. It also has some similarities to No Islands Tapa. There haven't been many variants that use different coloured clues. The rule is that all black clue squares are contained within the Tapa wall and white clue squares remain outside the Tapa wall. I now realise this is the exact opposite from Castle Wall, but I don't think it matters. The puzzle turned out well, in my opinion.

Rules for Tapa

This Tapa has black and white clue cells. White clue cells must always be outside the Tapa wall. You must always be able to reach the edge of the grid from them by travelling horizontally and vertically through uncoloured cells and/or clue cells. Black clue cells must always be inside the Tapa wall. You must not be able to reach the edge of the grid from them by travelling horizontally and vertically through uncoloured cells and/or clue cells.

Click to enlarge

Friday 8 January 2016

Puzzle #170: Tapa; Lonely

With the TVC having started again, I gave designing a few new variants a go. I find it more fun if a TVC has a few new variants in it. For the next 3 days I will post 3 new variants.

The first one is Lonely Tapa. This rule has already been in effect in one genre, namely Tapa Islands. This rule is that an orthogonally connected uncoloured area can only contain at most one clue cell. I was actually kind of surprised it wasn't already in this list as it seemed like such a simple rule. I think the puzzle worked out well.

Rules for Tapa

In this Tapa, any orthogonally connected uncoloured area can contain at most one clue cell.

Click to enlarge

Wednesday 6 January 2016


The first TVC of the season is over. I finished in 8th place, finishing all puzzles with 9 seconds to spare. It wasn't my best solve, but I'm still happy with it.
I had a bit of a slow start on the Alternative Tapa. I was a bit slow utilising the letters. I could have used uniqueness to finish it quicker, but I wasn't 100% sure if it held up. It just looked that uniqueness couldn't be guaranteed otherwise.
The next puzzle that caused problems was the second Skyscrapers Tapa. That was mostly because I forgot a 6 Tapa clue always needs one of two opposite edges coloured. I was treating it as a 5 clue and didn't see the opening. I got through I okay with a guess.
Then the Star Tapa held me up a bit, but luckily my own puzzle had given me some practise with the stars I needed here.
The last puzzle that caused problems was the second Magic Tapa. It actually caused the most problems and I had to restart it. Even on the restart I couldn't solve it, by which it was time to enter the codes. I was afraid I wouldn't solve it in time. But after entering the codes, I realised I had been treating a 2 as a 3 the whole time. So I could quickly solve the end and answer the key within a minute and claim my bonus of 0.2 points.

I think I got the most use out of designing my Tapa Star and Tapa Magic puzzles. I don't know which of my example puzzles were most useful for others. The feedback on my practise puzzles is getting less over the years. I don't know if it is because people don't need or want them anymore or if it's just because they have come to expect them. Some feedback would be appreciated as it takes a bit of work to push out all ten Tapas in the few days between the instruction booklet coming out and the start of the contest.

Lastly, the secret Tapa I mentioned in Part 2. The Tapa With Borders grid is also solvable as a 10x10 classic Tapa. I realised from the design that all outside clues were completely irrelevant to the Tapa with Borders logic. So I decided to clue them so that they would make a unique Tapa with the rest of the clues. I thought it was a fun touch.

Rules for Tapa

Click to enlarge

Sunday 3 January 2016

Daily League #54: Odd Sudoku

I had a few ideas for the next theme. One of them I couldn't really get to work the way I wanted. I had 2 puzzles that worked, but I didn't see me managing to find any more. Another theme has been done a few times by Fred Stalder, so I'll leave that one for later. The other theme might have been badly received by the same Fred Stalder, so I figured that's not the best way to start of the new year. So after rejecting a few themes, I settled on a simple one. This theme is Odd. It's not very original. As I don't write many classic variants, I figured it would be nice to write a simple variant for once.

The first puzzle is of course just a normal Odd Sudoku. I'm happy how it turned out. I think it looks nice with the four circle layout. It took a few tries as I kept having to add clues in other places to make it unique. It's not a hard puzzle, so it will probably be solved a lot more than some of my other puzzles. I hope people at least enjoy it.

Rules for Sudoku

In this Sudoku, grey cells must contain odd digits only.

Click to enlarge

Friday 1 January 2016

TVC XVII Practise: Part 2

Here's the second part of the practise puzzles for TVC XVII. I didn't have as much time to make puzzles during New Years. We also went to see the new Star Wars move today. That took up some more time. A few variants I had some trouble making, so that they would be a bit interesting. I think they should help getting used to the variants.

The first puzzle is an Alternative Tapa. It's not too hard a puzzle. I haven't found a good way to make this variant to be influential, instead of just using it to make the puzzle unique. At least it looks nice and still fun to solve.
The second puzzle is a Tapa with Borders. I thought making the size a bit smaller would make it a bit more interesting. Although a 6x6 Tapa is not very interesting. But finding the grid will take a bit longer.
The third puzzle is a TAPA LOGIC. I think this is a nice puzzle. It was at least fun to think of the logic involved here. It should be fun to solve too.
The fourth puzzle is a Make Room For Tapa. This one took a bit of effort to make. I first tried to make the rooms fit some randomly chosen clues, but I couldn't make that work. So instead I designed the rooms first and then figured out which clues would create a unique puzzle.
The fifth puzzle is a Tapa Star. This is definitely the hardest puzzle in the set. I kept coming up with puzzles without a valid Star distribution. It is easy to create a Tapa wall without a star pattern apparently. You really need to work the stars to get to the solution in this puzzle. Approach it carefully.

I hope this set is again helpful and enjoyable. Don't forget about the secret Tapa.

Puzzles can be found below.