There were few comments about including Twin Co-Ordinates in Marathon. Here are my thoughts on that topic.



I believe that visual puzzles are part of WPC-style puzzles, though they have been under represented in most contests / championships. If I have to pick couple of examples, the first one will be Puzzle GP finals 2015. There was a Find The Pair puzzle, which is similar to what we had here in Marathon. USPC has a visual puzzle every year worth 5 or 10 points, and similarly we have been trying to add visual puzzles in IPC for last 3-4 years. So I do not certainly feel Twin Co-ordinates puzzle was out of place in Marathon.

I also think Tawan did a wonderful job with the puzzle. While being less logical than others, you can also make step-by-step progress with this particular puzzle. Rohan has pointed that out in an earlier post. Have attached his partially solved solution to show what it means.



We also took extra precaution and asked for only 5 pairs, because we realized that it could sometimes be very frustrating to find all six. I would think that worked really well, which helped the puzzle be at almost similar difficulty as other puzzle. 185 players submitted this one successfully, out of which 112 got bonus. [ See statistics below to know which pair was the most difficult to find ]



When we (including Tawan) decided to include this type in marathon, we didn't expect to receive all positive feedback for the puzzle. That is exactly what happened, but I am glad that it made to top 3 favourite puzzle of several solvers.

Tawan, feel free to add your thoughts.

The authors get lot of credit for this. All authors were very accommodating and designed / agreed to adjust the difficulty level as per our requirements. We had four authors who even decided to write completely new puzzles because the difficulty level did not match with other puzzles. We already have seen one of them here in NEW, HUGE, AND CHALLENGING. I would like to thank all the authors again.

One puzzle - I would like to highlight - that lost bit of it aesthetics is the Neighbours. It had a perfect 12 clues across the diagonal, but we realized it is little too tough, so 4 clues got added at the end. The original version is pasted at the end of this post. [ The pdf file already has both the versions now. ] Thanks James for agreeing to distort this one.

We also got to add couple of clues to Domino Loop and Spiral Galaxy. Their original versions will be uploaded.

It was not mentioned in the IB, but the test solvers for this contest were Palmer Mebane and Rohan Rao. Thanks both of you. It certainly helps to have a top solver like Palmer as a test-solver, we could be very confident about the difficulty level of the puzzles before finalizing.

Original Neigbhours Version

(Emerges from hiding)

Looking at early WPCs and USPCs, visual puzzles have always been there. WPCs aren't limited to just logic puzzles - as long as they're language-neutral its fair game right? Which is also why I welcome the Casual section of the Puzzle GP with open arms.

So even if I feel visual puzzles deserve their place in these competitions - I won't try to argue about them being logical, cause I feel they're not. With this specific puzzle though, I did attempt to make it more methodological by adding areas where you can cross out to narrow down to the solution.

Initially there was a choice between a word or a visual puzzle. I sent Deb a list of potential candidates (list included scrabble, word search, spot the differences etc) and given the marathon format and the online medium - we decided on the Twins. For this particular fairy tale-themed puzzle (not culture-neutral?) I spent 2 three-hour sessions drawing it up on MS Paint. This is probably the most time (just under 6 hours total) I've ever spent making one puzzle. (Bonus points: can you name the stories where all the characters came from?)

The puzzle had two versions: the black/white one (that you solved) and one with colours (actually just different shades of gray) which should be somewhat easier. After seeing one solver guessing 231(!) times, I felt like hiding from LMI until the marathon was over. Congrats to Nishinanntoka who amazingly finish in just over 10 minutes.

As a competitor, I'm glad to snatch one first place in Sudoku from the Japanese solvers :). Also enjoyed the Futoshiki, Slitherlink was surprisingly fun and impressed at how James managed the LMI theme on the heavily-constrained Neighbours puzzle.

Your 3 most favorite puzzles of the contest.	Every Second Breakpoint
Your 3 most favorite puzzles of the contest.	Pentopia
Your 3 most favorite puzzles of the contest.	Neighbours
How balanced do you think the puzzle types of this test were?	Perfectly balanced
What did you think about the puzzle quality of the test?	Very nice
What is your opinion about rules, points and scoring for this test?	Fair

Your 3 most favorite puzzles of the contest.	Linked Poset Futoshiki
Your 3 most favorite puzzles of the contest.	Hidoku
Your 3 most favorite puzzles of the contest.	Pentopia
How balanced do you think the puzzle types of this test were?	Fairly balanced
What did you think about the puzzle quality of the test?	Very nice
What is your opinion about rules, points and scoring for this test?	Very fair

I enjoyed the puzzles, but didn't have time to finish all of them. It felt slightly easier than previous marathon sets.

Your 3 most favorite puzzles of the contest.	Neighbours
Your 3 most favorite puzzles of the contest.	Spiral Galaxy
Your 3 most favorite puzzles of the contest.	Hidoku
How balanced do you think the puzzle types of this test were?	Fairly balanced
What did you think about the puzzle quality of the test?	Fairly Nice

Your 3 most favorite puzzles of the contest.	Every Second Breakpoint
Your 3 most favorite puzzles of the contest.	Hex Slitherlink
Your 3 most favorite puzzles of the contest.	Linked Poset Futoshiki
How balanced do you think the puzzle types of this test were?	Perfectly balanced
What did you think about the puzzle quality of the test?	Very nice
What is your opinion about rules, points and scoring for this test?	Very fair

No congratulations for top solvers this time or I miss them? I am very satisfied with my performances and I had a lot of fun. Almost in all puzzles somehow I didn't feel big size of the grid. Maybe the organizers being carefully too much to avoid hard puzzles and possible complications. Thanks to all who are involved in this contest and congrats to Hideaki and Ken.