This past weekend, I made my annual pilgrimage to Cambridge for the MIT Mystery Hunt, a puzzle competition on a grand scale. Teams of up to 200 people attempt to be first to solve over a hundred puzzles and put the answers together to find a coin that has been hidden somewhere on the MIT campus. This past year, my team, Codex, won the Hunt, which means that by tradition, it was our turn to write and run the Hunt this year. It was an intense, exhausting, and deeply fulfilling experience.

I like to think of the Mystery Hunt as a gift economy. Each year’s Hunt is a gift given by the previous year’s winner to the other teams. I put in hundreds of hours writing and test-solving puzzles, plus an intense final sprint behind the scenes at Hunt HQ from Friday morning until late on Sunday. Codex’s leaders easily spent thousands of hours each making the Hunt come together. All of this was completely unpaid.

Why would any sane person sacrifice a year this way? Part of it is pride: just like solving a puzzle is a way to show off your cleverness, creating one lets you show off your creativity. But I think the reciprocal obligation that gift exchange creates best explains why every year the winners take on this tremendous burden. The winning team in a Hunt is the one that has most fully enjoyed the puzzles, that has been the greatest recipient of that year’s gift. This creates a social debt, one that can be repaid only with a return gift: another Hunt. Every year, teams joke that they will locate the coin, then walk away and leave it alone so that someone else can write the Hunt. No one ever does it: everyone understands what cheap move it would be.

This also explains something else. Each year’s Hunt is typically a little more ambitious than previous Hunts, on average. The overall number of puzzles has been rising with time, and the writing teams are always adding some new element. Last year’s Hunt had an incredibly clever structure, with unusually imaginative metapuzzles. (A metapuzzle is a puzzle based on combining the answers to other puzzles.) This year, we had teams come and put on fake Broadway productions. These something mores, I think, are a way for the writing team to demonstrate that it isn’t just returning exactly the gift it was given and is obligated to give back. They show that the Hunt, a labor of love, is freely given, that we chose to add something unique and not required.

This year’s Hunt theme was musical theater, as filtered through The Producers. It’s an apt metaphor: running the Hunt reminded me of working backstage on college theater productions. Everything is a complete disaster up through and including the dress rehearsal, but on opening night, everything always comes together in front of the curtain. I had the best seat in the house to appreciate the brilliance and inexhaustible work of my teammates, and to see the ingenuity and enthusiasm of the Hunters in the audience rising to the occasion. At the Hunt wrap-up — presented as an awards show for things like “Best Wrong Answer” — I found myself choking up. Getting to be part of a Mystery Hunt is an emotional, uplifting, humbling thing.

Some links:

• This year’s Hunt
• My photos
• Video of the kickoff
• Videos of teams’ performances
• Video of the wrap-up

And now for some details of the puzzles I worked on, and my favorite puzzles. Warning, some mild spoilers lie ahead:

Written by me:

• My favorite is 25th Annual Putnam County Debate Tournament. It requires solvers to classify the syllogisms hidden within a series of intentionally terrible arguments. The difficulty was slightly miscalibrated: many teams got stuck on the step of realizing that there were syllogisms involved, rather than on the more fun step of peeling away the informal arguments to find the (amusingly invalid) syllogisms within. It got called “this year’s WTF puzzle” by one solver.
• Tax in Space, was described by one reviewer as “straightforward(ish).” This puzzle started life as a logic problem that would actually use some real legal doctrine, and mutated repeatedly. In its final version, it’s a shaggy-dog puzzle: a long and convoluted joke. As a bonus, there are in-jokes for anyone who’s studied basic tax law (e.g. “Capital Gains” and “lower-case gains”).
• Raw Bar was a late-in-the-day idea. I was looking over a sushi menu and thought, “You know what looks kind of like a puzzle: sushi menus.” It seemed obvious that the ingredients in a roll could make a cryptogram, and from there, what could they be a cryptogram for? This one didn’t quite work; it was both too hard and too easy, even if the concept is decent.
• I also helped write a piece of the endgame, which isn’t yet online. As part of it, I got to dress up as Watson 2.0.

My favorite other puzzles:

• Potlines: A cute, well-executed idea. Once you have the “aha” about what the diagrams represent, what remains is just the right level of difficulty: doable but not trivial. The elegance of the illustrations makes this one work.
• The Measure of All Things: Nerdy but silly.
• Slash Fiction: Very nerdy and very silly. The idea is clever (although likely to be baffling if you don’t have computer experience), but the execution absolutely sells it. Seth and Vera took a secret four-day trip to Paris to film it.
• Yo Dawg, I Herd You Like Puzzle Hunts: A multiply recursive puzzle that requires no special expertise to solve, this one’s construction is absolutely brilliant. And it had the best title in the Hunt. Whenever we called a team about this puzzle, we’d lead off with “Yo Dawg, …”
• Paper Trail: A nice little diagramless crossword with a twist.
• Winning Conditions: Play with this for a bit, until you get the idea. Then try to win. Yeah, it’s devious. And fun.
• B.J. Blazkowicz in ‘Wintertime for Hitler’: Yes, it’s a Wolfenstein 3D / “Springtime for Hitler” mashup. And yes, it really is playable. And yes, it’s a good reminder about how much we’ve learned about FPS level design in the last two decades.
• Incredible Edibles: Another cute, well-executed idea. A good one for non-puzzle-experts to try their hands at.
• Critical Thinking: Like my puzzles, this one has a prominent humorous strain. But this one has an actual humorous payoff each time you make progress in solving it.
• Dawn of a New Era: Kai has a real gift for elegant puzzle mechanics. You’ll learn a lot in the course of solving this one.
• Collect Them All: Again, plenty of fun for non-experts.
• In Vivo and Makefiles: For heavy UNIX users only, but lots of fun for them.
• Twosquare: I helped fact-check this one, and it was plenty of fun. Prepare to watch some truly stunning magic tricks, I mean illusions. Be sure to read the alt-text on the images; it provides a significant but important hint.
• Picture an Acorn: Not only are the individual pictures fun to identify, but the extraction of the final answer is exceedingly clever.
• Itinerant People of America: I didn’t solve this one, and I admire anyone who can. Notable because we got John Hodgman to embed an important clue in one of his blog posts.
• The Voices in Your Head: Seth’s music puzzle.
• Stage Lines: Another elegant Kai construction.
• Award-Winning Poetry: Another puzzle whose humor is perfectly embedded. Broadway musical fans have a shot at this one; anyone else should just keep moving on.
• Carb Pool: We gave each team two bags of pasta: one intact and one broken. And just to be sure that they didn’t think the number of pieces was important, we broke it in front of them, violently. This one required several hours of cutting dry pasta by hand. Here’s a photo:

• Set Theory: Not a novel idea, not that difficult, very well-executed.
• Cross-Breeding: A puzzle whose implementation perfectly reflects its concept.
• Course 7E: The first puzzle I test-solved, and still a favorite. Not quite “funny” per se, but definitely enjoyable.
• Functions: Arguably the most widely admired puzzle in the Hunt, judging by the number of Codexians who were raving about it.
• Rats: You had to see Michael (an actual MIT alumni interviewer) in action to get the most out of this one, but having a interview to be admitted to the second half of the puzzle was an idea of loopy genius.
• Sovereignty: I fact-checked and helped edit this puzzle, and in its final form it requires some very nice logical reasoning. Per the references to “players,” should probably not be attempted by non-gamers.
• Argh: Like Andrew, I couldn’t believe this one hadn’t been done before. But it hadn’t, and now it has been, and in style.
• Cookin: Another fun-for-all food puzzle.
• JFK SHAGS A SAD SLIM LASS: Yes, this puzzle has no content. Yes, it’s solvable.
• Encoded: I haven’t otherwise coded in at least a year, but I installed two programming environments and learned some new libraries to do this one.
• Screen Test: I like the concept, but I couldn’t have solved this one alone.

My favorites metapuzzles were:

• Charles Lutwidge Dodgson: play chess and Scrabble simultaneously, each with a hidden twist. I spend a day grinding through the chess half during test-solving, and never noticed the time flying by.
• Into the Woodstock: Aha-based, but both clever and fair.
• William S. Bergman: Mad wordplay in the house.
• Mayan Fair Lady: Manages to combine the two source elements in the show in a surprising but highly amusing way.
• Ben Bitdiddle: Here’s a bag of parts; hope you brought a soldering iron like we told you to.
• Ogre of La Mancha: Worth it for the answer alone.