## Mathy Puzzles at 2018 MIT Mystery Hunt

I was on the writing team for the 2018 MIT Mystery Hunt. I am pleased that the hunt got very positive reviews from the participants. I spent tons of hours working on the hunt and it is good that folks liked it. I edited and tested a lot of puzzles. Here is my review of these year’s puzzles that are math-related.

I already posted an essay about the puzzles I wrote myself. Four of my five puzzles are math-related, so I am including them below for completeness. I will mention the topic of each puzzle unless it is a spoiler.

I start with Nikoli-type puzzles. Four elegant Nikoli-type puzzles were written or cowritten by Denis Auroux. In all of them the rules of the logic are stated at the beginning. That means the logic part doesn’t contain a mystery and can be solved directly.

- Good Fences Make Sad and Disgusted Neighbors (by Denis Auroux). You can guess by the title that this puzzle was in the emotions round corresponding to sadness and disgust. This is an interesting variation on the hexagonal Slitherlink. This is a relatively easy puzzle.
- Shoal Patrol (by Denis Auroux and James Douberley). Each grid is a combination of Battleship, Minesweeper, and a loop puzzle. These are difficult, but satisfying puzzles. The extraction step is not mathematical and not completely trivial.
- Submarine Patrol (by Denis Auroux and James Douberley). This is a 3D version of Shoal Patrol.
- Hashiwokakuro (Count your bridges) (by Denis Auroux). This is a mixture of Hashi and Kakuro. I enjoyed the puzzle while I tested it. The extraction is trivial.
- A Learning Path (by Tanya Khovanova and Xavid). This is a path logic puzzle that was targeted for new hunters. It contains self-referencing hints and solving techniques.

There were several puzzles that were very mathematical.

- X Marks the Spot (by Zachary Chroman). A very non-trivial puzzle about triangle centers.
- Tournament Organization (by Scott Harvey-Arnold ). A tournament reconstruction puzzle.
- Cash Cab (by Erica Newman and Justin Melvin).
- Voter Fraud (By Ben Weissmann). A voting puzzle.
- The 10,000 Puzzle Tesseract (by Charles Steinhardt, Zachary Chroman, and Scott Harvey-Arnold ). The most difficult puzzle of the hunt, by far.
- Games Club (by Tanya Khovanova and Sergei Bernstein). This puzzle is about combinatorial two-player games.
- Murder at the Asylum (by Tanya Khovanova). This is a difficult puzzle about liars and truth-tellers.
- Studies in Two-Factor Authentication (by Brandon Avila). A very elegant puzzle, that is one of my favorites.

There were also some math-related or computer-sciency puzzles.

- The Next Generation (by Colin Liotta). I enjoyed being an editor of this puzzle.
- Disorientation (by Alex Churchill). This puzzle has a beautiful visual component.
- Message in a Bottle (by Nathan Fung). The puzzle doesn’t look like it has something to do with mathematics, but my testing of it was very satisfying. I guessed from the start what it was about.
- Self-Referential Mania (by Justin Melvin). Self-referential logic puzzle, which I enjoyed editing.
- Bark Ode (by Elizabeth French, Justin Melvin, and Erica Newman). The pictures are so cute.
- Executive Relationship Commandments (by Robin Deits, John Toomey, and Michele Pratusevich). I didn’t see this puzzle until after the hunt. I wish I could have tested this puzzle with my son Alexey, who is a computer scientist.

There were also several decryption puzzles:

- Word Search (by Tanya Khovanova). A crypto word search.
- Texts From Mom (by Elizabeth French and Justin Melvin ). A text enciphered with emojis.
- Marked Deck (by Colin Liotta and Leland Aldridge). One of my favorite puzzles. Hunters received a physucal deck of cards that was laser cut. You can buy the deck at Etsy. The art in this puzzle is beautiful, but the puzzle also has a non-trivial decryption step.