Fillomino and Ripple Effect are Reader’s Choices

Before the end of Nikoli Hurdles 2, a poll was opened for a couple of weeks to determine two puzzles for the next edition. Five puzzle types, all from filling-in-numbers genre, were listed and we have an outright winner.


People sure love their Fillominos!

With twice as many votes than the second most popular type, it would be a sin to exclude it from the next set of hurdles. At a distant second is Ripple Effect, a type where I have explored a while back. I will promise to include them as Reader’s Choice next time.

I’m not promising any dates for Nikoli Hurdles 3 as they are other events down the pipeline.

Do look forward to them and thank you for voting!

Solutions to Nikoli Hurdles 2 – Part 5/5

kanaorepuzPuzzle 8: Kanaore
Too many errors prevented me from being happy about this puzzle. One is that Wall-E had 1941 next to it for a few days before I noticed it. It was clearly copy and pasted from Dumbo’s year of production. The initial diagram had the “7” arrow pointing the wrong way which led to impossible solutions which halted many solvers. To make matters even worse, the wrong diagonal was shaded for the answer keys so no one could reach the finish line!

Repairable mistakes but nothing could prepare me for… that darn N!

Kanaores are solved on empty grids. They should not have any givens, but the mistake was so disgustingly severe I had no other options but to dismantle the entire puzzle which I was not keen on doing. I completely overlooked the N despite test solving it twice! Maybe I was too excited that the bottom half of the puzzle squeezed itself into uniqueness, I forgot that the N from ALADDIN could sneak its way back to grab the N from TARZAN.


Had none of the above happened, I would look back at this puzzle and be rightly proud of it. I looked at a few examples from Grant Fikes’ blog (he uses the name “Seek and Spell”) and started brainstorming ideas. I wrote this puzzle in a coffee shop during the time when no matter where you went, they would open “Let It Go” from Frozen. I must have subconsciously come up with the idea then.

Looking back at the puzzle I am still slightly irked by that N.
Hopefully by next year I would finally let it go.

Let it go… Let it go….

Solutions to Nikoli Hurdles 2 – Part 4/5


Puzzle 6: Five Cells
From the inclusion of Five Cells, I learnt that the world needs more of them. I have been solving a lot of Five Cells in Nikoli magazines so I took it for granted that it was a well-known type. Imagine my surprise when I was showered with praise for this puzzle!

Adam Dewberry: Particularly enjoyed number 6  :)

Rakesh Rai: I liked the sixth puzzle (five cells) the most, perhaps because it was new for me.

John Reid: Five Cells was also very entertaining for me as I don’t think I’ve seen that type before.

In a usual Nikoli magazine, Five Cells are scattered with 0’s. Even the hard ones are littered with 0’s. That’s an instant X-pentomino wherever you see a 0. If that’s not easy enough; how about a generous amount of 3s all around the perimeter?
Seriously, Nikoli?

So I came up with one without 0s and a lot less clues around the border. The middle of the puzzle is where all the challenge is at. Although, I don’t think it was that tough given how quickly you can try twisting the pieces in your head and fixing trial and errors.

5cellsanswerPuzzle 7: Kurodoko
This puzzle was written in a hotel way back in March, I remember this because it was written in my grid-squared diary. When I came round to edit the puzzle it broke no less than three times. According to my own test solving, this was the hardest puzzle in Nikoli Hurdles 2. The theme I was trying to work on was that each trio of clues sums up to 10. We have 8+2=10, 7+3=10, 6+4=10 and a scattered 5+5=10.


The puzzle revolves around the centre’s 10 diagonally adjacent to the 2. There are two possible configurations but one will only work when you consider the 5s at the bottom. I felt that during a timed competition, guess-and-check beats logic in this particular puzzle.



Solutions to Nikoli Hurdles 2 – Part 3/5


Puzzle 5: Select Words
A word puzzle!
As with all surprises; it can either mean a pleasant one or a bad surprise. If you are a purely logic puzzle fan expecting a run of nothing but logic puzzles, your reaction might be getting slapped in the face with a word puzzle. Otherwise, Select Words might come as a nice little gift before Christmas. If you can overcome the intimidating factor of the unexpectedness, you might find that the puzzle wasn’t that hard after all, as solver Alan O’Donnell indicated, “Round 5 was a little out of character though – non-logical is ok, but it was trivially easy.”

And it had to be easy. A lot of my audience does not primarily use English, including Matej Uher, “the hardest puzzle, at least for me, was obviously Select Words, because I am not a native speaker”.
I’m sure he wasn’t alone. Thank you all for persevering through it though!

In case you don’t know, original Select Words are done in Japanese. I know enough Katakanas to do some if any of the puzzles used English-derived Japanese words. Thomas Powell who almost won Nikoli Hurdles 2 said: “Thanks for not doing the Select Words in Japanese :D”. Now wouldn’t that be a fun exercise?

Select Words appear individually in Nikoli Puzzle Communication magazines. I thought about how I could present several puzzles and still have only one answer key. The idea of linking them up suggested itself. I have 3 puzzles that feed their answers to the 4th puzzle.

The smallest puzzle using 5-letter words were all instruments. The 6-letter puzzle used zodiac star signs. My choice was limited and a couple of words have similar patterns so no matter how hard I tried to anagram them, the solutions seemed all too clear. The 7-letter puzzle used animals with nothing obvious in common apart from all having 4 legs. I originally had DOLPHIN and OCTOPUS then stared at the ceiling for too long to come up with anymore sea creatures that were better than ANEMONE.

The final puzzle entries were 5-letter countries. The shaded letters can be scrambled to spell out ITALY, which was the final answer.

Puzzles from Nikoli Hurdles 2 can be found here

Solutions to Nikoli Hurdles 2 – Part 2/5


Puzzle 3: LITS
You may or may not notice the four crosses I laid near the centre of the grid as a start when making this LITS. It is similar to the idea of the Country Road in the last Nikoli Hurdles. There are a few five-cell regions in this puzzle which should give solvers sufficient toeholds to complete the puzzle.

I wanted to make a 10×10 grid but it didn’t work out. I caught a lucky break when the 11-cell region at the upper right had only one possible solution. After tweaking the puzzle for a few minutes, I called it a day and immediately wall off the right hand side of the grid. The result was not too bad right?


Puzzle 4: Slitherlink
The other winner at the Reader’s Choice poll was Slitherlink. Among the most-common puzzle types, this type has to be my worst. I can’t solve Slitherlink, or any variants of Fences for that matter, even if my life depended on it. I tried practicing, I purchased a whole book of Slitherlink, I timed myself and I just never seem to enjoy Slitherlink. This applies to Turning Fences, Polygraph and any other variants (Liar, Pentomino etcetera) that originate from it. I choke when I see dotty grids in any instruction booklets. European puzzle makers are notorious for making Slitherlinks.

No matter how much I dislike it, if the readers prefer so, I shall deliver. My Slitherlink has very little obvious steps; there are no 3s next to 0s, no adjacent 3s, no two 1s in a corner and so forth. The borders should solve quite easily and linking the middle portion of the grid was all there was to the puzzle. Quick intuition is always faster than solving Slitherlink logically anyway, so I suspect most of you did that. A flick through my puzzle shed revealed that this was my very first (!) classic Slitherlink. This puzzle won’t be seeing any of its relative for a while.

Puzzles from Nikoli Hurdles 2 can be found here.

Solutions to Nikoli Hurdles 2 – Part 1/5

Puzzle 1: Masyu

Last year I conducted a poll asking for favourite Nikoli types. Masyu and Slitherlink were the two winners and became the Reader’s Choice for this edition of Nikoli Hurdles.

I quickly whipped up a 10×10 easy Masyu for Puzzle 1. The puzzle looked so boring that I decided to inject a bit more life into it. I aimed for a complete set of pentomino pieces in the givens but the grid was too big for uniqueness. I had to add more pieces and a few circles to get a valid puzzle.


A straight-forward solve to start the first 100m of the track


Puzzle 2: Yajilin
I picked one puzzle from the last Nikoli Hurdles to feature here and it was a Yajilin. An error posed a problem for early solvers when I had a 3 mistyped as a 2. Funnily, Prasanna who ran into the error; correctly assumed I had a typo and just tweaked the puzzle himself!

He continued the track without me even fixing it in time. About the solving, I thought it was a nice Yajilin with clue symmetry. Grandmaster Puzzles recommend using unclued grey boxes in Yajilins in which I can’t say I agree to. Those remind me of “cheater black squares” in American crossword puzzles. They’re there to make the author’s life easier while preserving the puzzle, which I don’t think is a pretty thing to do.

A fairly difficult solve as solver Ivan Koswara vaguely remembered: “I think I recall the Yajilin being extremely tough or something.”

Full PDF of Nikoli Hurdles 2: here

Results of Nikoli Hurdles 2

It has been an exciting 29 days and the track is now closed. To determine the winner, all competitors that have reached the finish line took part in Minority Decides, where everyone picks a choice of answers and the minority will prevail. Last time we played Minority Decides was during Race up the Sky, where only 17 people participated. We have more than twice that many since I have received 44 entries to Nikoli Hurdles 2.

Here is the list of entries in the order of submission:

  1. Prasanna Seshadri
  2. Swaroop Guggilam
  3. Ashish Kumar
  4. Edison He
  5. Stefan Tomlins
  6. Sky Net
  7. Nick Brady
  8. Raphael Lehrer
  9. Matej Uher
  10. Walker Anderson
  11. Thomas Powell
  12. Liane Robinson
  13. Ken Levine
  14. Nikola Zivanovic
  15. Adam Dewberry
  16. Dylan Gibbs
  17. James McGowan
  18. Alan O’Donnell
  19. Alberto Fabris
  20. Rakesh Rai
  21. Gareth Moore
  22. Emma McCaughan
  23. Nick Deller
  24. Michael Mosshammer
  25. Jakub Hrazdira
  26. Robert Vollmert
  27. John Reid
  28. Grayson Holmes
  29. Michael Collins
  30. Katarina Cvenic
  31. Daniel Cohen
  32. Hayashi Makoto
  33. Jakub Ondrousek
  34. Ivan Koswara
  35. Way Tan
  36. Jack Bross
  37. Andrew Brecher
  38. David Cohen
  39. Ruben Gafencu
  40. Maja Gribajcevic
  41. Peter Bereolos
  42. Alan Lemm
  43. Yuhei Kusui
  44. Salih Alan

That’s a long list!
I’m not complaining, the more the merrier. If you are one of the 44 listed above, note your number and follow your progress below.
Let’s play Minority Decides!

Question 1: Now that you’ve completed the track, what are you going to do now?
A: I think I’ll take a nap now
B: I’m going to find more puzzles to solve!
nh2resa20 people chose answer A,
24 people chose answer B.
The correct answer is A! 
20 nappers moving on.

Question 2: Did you wake up late this morning?
A: Late? I’m always on time
B: Yea, I slept through 4 alarms
nh2resb11 people chose answer A,
9 people chose answer B.
The correct answer is B! 
9 people who not only chose napping over puzzling, but also late-wakers, are moving on!

Question 3: What do you do when you have trouble sleeping?
A: Listen to music
B: Count sheep

6 people chose answer A,
3 people chose answer B.
The correct answer is B! 
We are down to our final three! Well done sheep-counters!

Question 4: You’re on an African safari trip, what’s that on your left?
A: A pride of roaring lions
B: A herd of stampeding elephants

0 people chose answer A,
3 people chose answer B.
No correct answer! 
No one is bulging.
Let’s introduce our final 3:
Stefan Tomlins is still exercising his beginner’s luck since July Giants, held a few months ago, was his very first event here at SOTR. On the other hand, Thomas Powell submitted a fair number of entries at my blog. He knows what winning feels like, since he became one of the shared winners of Anchors Aweigh earlier this year. Finally Salih Alan, wearing the number 44, sent his entry just a few minutes before I closed the contest. Close call! Salih is all too familiar with my puzzles, as he edits them for Akil Oyunlari several times a year. Good to see him entering my contest for the first time. Let’s see who will win!

Question 5: How do you prefer solving puzzles?
A: Pencil and paper
B: On electronic devices
nh2rese0 people chose answer A,
3 people chose answer B.
No correct answer! 
Oh come on guys. Move around a bit more!

Question 6: How is the year going for you?
A: I’ve done a lot in 2014, can’t wait for 2015!
B: It’s October already? I wish time would slow down

1 person chose answer A,
2 people chose answer B.
The correct answer is A! 

Congratulations to Stefan Tomlins from New Zealand!
He will receive the latest Nikoli Penpa 2015 which will be published early next month. You, too, can win as long as you enter! So if you missed out, come back next time.

That is it for Nikoli Hurdles 2, thanks for being with me throughout October.
Here are the 8 puzzles combined in this PDF right here
As usual, answers and little notes about each puzzle will be posted in the next few posts.
I’m already writing puzzles for future events and hope to see you all there again. Check back regularly for puzzle-related posts and notices about upcoming contests. Even better, subscribe to SOTR and have all updates sent to your inbox!

Happy Halloween!


Nikoli Hurdles 2: Last stretch

nh2offbannerOnly 5 days to go!
I have sent replies to all entries that I’ve received thus far. If you believe you have submitted but have not yet receive an e-mail from me, please resend your entry.
rcroyYou may have noticed the label: “Reader’s Choice” in Masyu and Slitherlink. Reader’s Choice provides an opportunity to make sure your favourite puzzle appear in the next set of hurdles. Below are five number-filling puzzle types.
Which puzzles would you like to see in Nikoli Hurdles 3?
I’ll collect your votes and announce the tally later on. You can choose up to 3 types.

[Poll is now closed]

Check back in a few days for the announcing of Nikoli Hurdles 2 results!

Half way to go


We are approaching half way into Nikoli Hurdles 2. All entries that were sent in have been replied to.
I usually take up to 3 days to send a reply, so if you have submitted an entry and not yet receive a confirmation e-mail – please resend your entry.
Also, make sure to spell your e-mail address correctly, otherwise my reply might not reach you.
Thank you all for the entries that are coming in, I enjoy keeping a tally of your records.

If you have any worries, feel free to send me an e-mail about it.
Happy puzzling!

Runners, welcome!


Welcome to another set of Nikoli Hurdles!
For the next 29 days, a track of 8 Nikoli puzzles will be opened for you to solve. Starting at Puzzle 1, the solution will be used to open Puzzle 2. The answer to Puzzle 2 will open Puzzle 3 and so on.

The different puzzle types will require different answer key extractions so pay attention to those. An entry form will be at the finish line for those who complete the entire track. More details can be found at the About page on the menu above.
Don’t forget to use capital letters, when required.

I will always be available to answer questions, so you can drop those in the comments or email me at roygbivpuzzles (at) gmail (dot) com. A prize will go to one lucky winner after this event ends.

ETA (27/9/14): 8 hours into the contest, early runners had sent me problems about some of the puzzles.
Puzzle 2 had a little tweak in one of its clues, I’m surprised people could still proceed. The last Puzzle 8 had one slight drawing error. Both puzzles have been fixed. Puzzle 7 was questioned as well, but upon reinspection, it is not broken and has a unique solution.
The finish line had the wrong password for about 8 hours, but it is now fixed. I apologize for all these mistakes.