Best puzzles of 2019 Q1 (January - March)?

Question

This question is part of the best-puzzle award series.

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What are your nominations for the best puzzles, here on Puzzling.SE, of the first quarter ( January / February / March ) 2019?

Suggested guidelines for nomination:

• Nominate each individual puzzle in a separate answer, so they can be upvoted/downvoted separately.

• No more than 3 nominations per person.

• Don't nominate your own puzzles.

• Before you nominate a puzzle, check to see if someone else has already nominated it. If they have, then add to that nomination as a comment (or edit it) instead of nominating the same puzzle again.

• In your nomination, explain what it is that (in your opinion) makes the nominated puzzle such a good one.

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Some lists to help jog your memory (your nomination doesn't have to be from these lists):

• Algorithmically selected "best of":
  • Popular puzzles, both in score and in vote to view ratio, from 2019 Q1
  • Well received puzzles you may have missed from 2019 Q1
• Best by votes/views:
  • Questions with the most votes from 2019 Q1
  • Questions with the most views from 2019 Q1
  • Questions with the highest-voted answers from 2019 Q1

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_{Meta-meta issues:}

• _{Is this kind of thing allowed on SE?}

  • _{Yes, Photography SE and Sci-fi/Fantasy SE do something very similar.}

• _{What's the point?}

  • _{To highlight and encourage good practice in a way that goes beyond upvotes.}
  • _{To work towards building a 'hall of fame' of some of the best puzzles on the site (perhaps to reside on a future puzzling.SE blog) - think of it as our 'greatest hits album'.}
  • _{To prompt members to put forward their own reflections on what makes a high-quality puzzle.}

Answer 1

A Missing Symbol for This Logo by athin

This was a very clever and amazingly creative puzzle by athin. Also, it was one of the first puzzles I saw on joining this site, and was indeed the best first impression it could be.

Answer 2

The mother of all age-of-the-captain riddles by Arnaud Mortier

Solving this one requires a combination of arithmetic, logical deduction and some pretty obscure historical knowledge. The real punch is the unexpected question statement, which at first glance seems like it can't possibly have any relation to the clues given. This changes the puzzle from a simple calculation ("oh, I need to find number x with these properties") to a real mystery. Finally making the connection required to solve the puzzle gives a satisfying "a-ha" feeling, and we get to learn a neat new bit of trivia in the process.

Answer 3

Emojional cryptic crossword by jafe

There were several variations on cryptic crosswords posted by jafe in the first quarter which are worthy of nomination for the sheer work that must have gone into constructing them.

This one stands out for me for its unusual twist on the classic theme.

Answer 4

"Murder!", said the knight by Arnaud Mortier

A wonderful chess puzzle (with 28 upvotes) from Arnaud Mortier that I highly enjoyed solving. This is hands-down the best puzzle for which I had the honor of receiving the green checkmark.