We need a strategy to deal with a hydra. Its Sunday, January 14, 2024, more than 50 hours since the annual MIT Mystery Hunt kicked off at noon on Friday, and Setec Astronomy is one of more than 200 teams racing to solve hundreds of puzzles over three days. The 60-some members of Setec, many of whom are joining remotely from as far away as Australia, are making good progress, even though many of us are running on limited sleep and questionable nutritional decisions. Several of the chalkboards in the Building 2 classroom weve been assigned for our team headquarters are covered in lists of puzzle solutions or messy diagrams charting out theories about how to crack the various challengesall of them constructed, as Mystery Hunt tradition dictates, by the most recent winner, in this case The Team Formerly Known as the Team to Be Named Later. The hydra were dealing with is a metapuzzle: We have to find a way to use the solutions from other puzzles that weve already solved to extract one more answer. If we solve this one, well be rewarded with more puzzles. We know we need to diagram the answers for this round of puzzles as a binary tree. In keeping with the hydra metapuzzles mythological analogue, every time we solve one puzzle, two more branch off until we have a diagram five levels deep. Were still missing answers from several unsolved puzzles that would help us figure out how the diagram works and how to extract an answer to the metapuzzle. The diagram weve drawn, in green chalk, gets more chaotic with every addition, erasure, and annotation we squeeze onto the overcrowded chalkboard. But we can sense that were just one aha! away from a solution. MITs Mystery Hunt has been challenging puzzle enthusiasts every year since Brad Schaefer 78, PhD 83, wrote 12 subclues on a single sheet of paper as a challenge for friends during Independent Activities Period (IAP) in 1981. The answers led solvers to an Indian Head penny he had hidden on campus. Todays Hunts are still built around that basic concept, but what constitutes a challenge has changed over four decades. One of the clues from the original 1981 Hunt is just a missing word in a quote: He that plays the king shall be _____; his majesty shall have tribute of me. Its easy to solve today with Google, but in 1981, even if you knew it was Shakespeare, if you didnt notice the subtle hint that you should look for a character referring to a play within the play, it might have taken a few hours of skimming the Bards collected works to find the answer. The Setec Astronomy team tries to map out whether the human knot theyve gotten themselves into can be untangled.JADE CHONGSATHAPORNPONG 24/MIT TECHNIQUE We add a few more solutions to the hydra diagram over the next few hours. Eventually someone notices that all the answers in the fifth level of the diagram seem to have an odd prevalence of Ls and Rs. This is the aha! moment: They tell us how to navigate the binary tree. From the first node at the top of the tree, we follow the Ls and Rs in the order they appear in each of the 16 solutions on the fifth level. Take the left branch, then right, then left again, landing on a word that starts with H. The second fifth-level answer leads us to a word that starts with E. Repeating the process with all 16 answers spells out an apt way to deal with a hydra: HEADTOHEADBATTLE. (Puzzle solutions are traditionally written in all caps with no spaces or punctuation.) Those of us whove been tackling the puzzle take a moment to enjoy our victory before splitting up to find new puzzles to work on. Some elements of the Mystery Hunt are hard to describe, the kind of must-be-seen ingenuity that also inspires hacks on the Great Dome and any number of above-and-beyond engineering projects showcased around campus every year. Most of the puzzles are utterly unique, although they do often incorporate logic and word problems as well as more mainstream elements like crosswords, sudoku, and Wordle. But almost anything can be turned into a puzzle. For example, chess puzzles might be combined with the card game Magic: The Gathering. Or solvers could be asked to organize a Git repository with 10,000 out-of-order commits (that is, find the correct sequence of 10,000 changes to a file as it was tracked in a version control system), identify duets from musicals, or draw on their knowledge of pop culture trivia. For most of its history, the Mystery Hunt had little official status on campus. By tradition as much as any organizational effort, teams simply showed up in Lobby 7 on the Friday before the Martin Luther King Jr. holiday for the kickoff. In 2014, the MIT Puzzle Club was formed to help provide year-to-year continuity and other support, such as securing rooms for teams to work in and reserving Kresge Auditorium for the opening ceremonies. Puzzle Club also hosts other events, such as mini puzzle hunts and sudoku and logic puzzle competitionswhich Becca Chang 26, the clubs current president, says has helped a lot with outreach to new students or anyone who might be interested in [puzzles]. Technology has enabled the Mystery Hunt to grow and evolve in significant ways, and not just in terms of the kinds of puzzles that are possible. Through the mid-1990s, a single person could take on the responsibility of writing and running the event. Today its a yearlong commitment for the winning team to design the next years Hunt. Doing so requires managing creative output and technological infrastructure that rival those of a small business. Duties include spending thousands of hours writing and testing puzzles, constructing physical puzzles and props, and building a dynamic website that can withstand the huge influx of puzzle-hungry visitors. Todays Hunts are built around a story. Here John Bromels as the god Neptune checks in on Galactic Trendsetters progress to restore the god Pluto after his planet was demoted.JADE CHONGSATHAPORNPONG 24/MIT TECHNIQUE Just organizing a team of solvers can be a major undertaking, especially now that more and more participants are joining remotely. Anjali Tripathi 09, who started the team Im Not a Planet Either in 2015, got her introduction to puzzle hunts through a miniature Mystery Hunt that Simmons Hall runs for first-years. After tackling the main event with the Simmons team on campus as an undergrad, she participated remotely for the first time in 2010. I was abroad in England and still wanted to do Hunt, and I remember how hard that was, she says. The team had no infrastructure for it. Its about connecting with other humans thats why we do it. Erin Rhode 04, whose team name one year was the entire text of Ayn Rands Atlas Shrugged Today, solvers can work together across the room or across a continent. Platforms like Slack and Discord have become indispensable to many teams, which use them for updates and announcements as well as creating separate channels where people can tackle a given puzzle together. Many teams use applications that organize the convoluted deluge of puzzles into a workflow so everyone can see which have been solved, which need attention, and whos working on what. Google Docs and Google Sheets make it easy for multiple people to contribute to progress on the same puzzle whether theyre sitting side by side on campus or are separated by several time zones. I think especially post-2020, there is just the expectation that everything is going to be accessible online, says Tripathi, who still has a Hunt-related Google doc from 2008, just a couple of years after the service launched. But even as the Mystery Hunt has adapted to the internetand to increasingly powerful search engines, smartphones, the Zoom era, and even some machine-learning applicationsat its core it remains a very human experience. Its about connecting with other humansthats why we do it, says Erin Rhode 04, a longtime Mystery Hunter whose team has won twice. She recalls being inducted into the Hunt as a first-year in 2001. An upperclassman came in and was like, Youre coming to the math majors lounge. Were doing this puzzle hunt thing. The name of Rhodes team changes every year, though they might be best known for the year their name was the entire text of Ayn Rands Atlas Shrugged. Last year, they were . (Thats not a typo or a missing wordits the zero-width space, a Unicode non-character primarily used in document formatting.) Early Mystery Hunts led solvers to an Indian Head penny hidden on campus. Today, winning teams are awarded coins unique to each years Hunt. Ringed with a repeating MH24, the 2024 coin shows the cities teams visited on their quest.JADE CHONGSATHAPORNPONG 24/MIT TECHNIQUE Like so much of the Hunt, team names are an exercise in creativity. The full name of the team running the 2024 Mystery Hunt was officially The Team Formerly Known as the Team Formerly Known as the Team Formerly Known as the Team Formerly Known as the Team Formerly Known as the Team to Be Named Later. Some teams keep their name every year, like Setec Astronomy (an anagram for too many secrets, in a reference to the classic 1992 heist film Sneakers). Others change every year or every few years, or when teams merge, as when Death from Above joined forces with Project Electric Mayhem to become Death and Mayhem. Rhode remembers one particular puzzle from her first Hunt that she and her team (known that year as the Vermicious Knids) worked on through the night. They had to figure out that a list of enigmatic phrases were clues to song titles. For example, Of course; you just go north on Highway 101 clued the song Do You Know the Way to San Jose? I think today, we would have solved that puzzle in about an hour, Rhode says. There werent song lyric databases back then. And so it was a lot more sitting around on your own trying to come up with songs as opposed to just finding some master list and then searching it. Writing puzzles with the knowledge that solvers will have a slew of tools at hand is just part of the process. Use whatever technology you have at your disposal to solve the puzzle is the general rule of thumb, says Jon Schneider 13, a machine-learning researcher who hunts with Galactic Trendsetters . (The in their team name is pronounced like a plane taking off and landing, respectively.) Schneider has been hunting since 2010, when it was common for solvers to have to identify clips of songs or other audio. Hes seen that change in the past decade, though: Audio recognition [technology] like Shazam has become a thing, so its harder to create puzzles that require the skill of music recognition. When youre a constructor, you try to figure out: What is my challenge for the solver? says Dan Katz 03. Katz has solved and written a lot of puzzles. (In fact, he created a five-puzzle mini Hunt for this issues Puzzle Corner.) He attended his first Mystery Hunt in 1998, as a junior in high school, before he had even applied to MIT. Hes been part of a winning team eight times (probably a record) and competes in events like the World Sudoku Championship and US Puzzle Championship. In Katzs view, technology should make puzzling more interesting for the solver. While solvers might need to, say, code a program, organize information in a spreadsheet, or navigate a video-game-like interface to arrive at an answer, what he prizes most is the mental challenge of figuring out how to solve a puzzle. During whats known as the Mid-Hunt Runaround, a team follows a set of cryptic instructions that lead them on a subterranean journey across campus.JADE CHONGSATHAPORNPONG 24/MIT TECHNIQUE Rhode misses the days before an app was able to listen to a few seconds of a song and identify it. One of my superpowers in the early days of the Hunt was: Play me a bunch of pop songs and I can identify like 90% of them, she says. Now everybodys got Shazam on their phone. And so as fast as I might be, Shazam was always going to be faster. That doesnt mean puzzles cant be based on song identificationor image identification, another common puzzle element that has been made trivial by tools like Googles image search capabilities. It just means constructors must become more creative. You have to obscure the images or the music in such a way that the technology cant find it quickly, Rhode says. She describes a puzzle she wrote when she wanted solvers to identify songs without using technology: I arranged eight songs a cappella and sang them myself, but buzzing like a bee. And the whole idea was you cant Shazam that. Schneiders team took a similar approach to constructing a puzzle in which solvers had to identify specific visual artistsnot by their work, but by their distinctive style. Solvers were prompted to upload an image of their choosing, and a generative AI tool similar to DALL-E rendered it in the style of the artist they were supposed to name. I mostly justwant to be surprised. Jon Schneider 13 of the team Galactic Trendsetters Thats not the only puzzle to have incorporated some machine-learning elements in the last few years. A few examples have used semantic similarity scoring systems where solvers have to guess words or phrasesa kind of machine-learning-enabled version of hot or cold. Even if machine learning has potential as a tool for puzzle constructors, generative AI is unlikely to solve Mystery Hunt puzzles anytime soon. ChatGPT can answer questions that might be helpful in getting started and maybe even help solve a crossword clue or two, but the puzzles are often so unusual that it doesnt know where to begin. When presented with them, it usually responds by stating that it would need more context or clues in order to proceed. Schneider did find ChatGPT very helpful, though, in solving a nonMystery Hunt puzzle about navigating the byzantine rules of the role-playing game Dungeons & Dragons, which he admits hes never played. A few years ago, there would have been no way around spending hours digging through the rulebooks and figuring out each step, but giving the puzzle to ChatGPT worked. It was really good at doing this. I guess it had trained on enough data of people playing Dungeons & Dragons that this was within its capabilities, he says. Schneider is optimistic that new technology will be integrated into Mystery Hunt in creative ways, expanding the scope of what puzzle constructors can come up with to entertain solvers. Ultimately, he says, I mostly just want to be surprised. As the sun sets on Sunday, Setec continues solving puzzles at a steady pace, but were also still unlocking new sections of the Hunta sign that were still some distance from the endgame, though rumors (but never spoilers) from friends on other teams suggest that a few teams might be closing in. As midnight rolls around theres still no announcement, and so we push on. Ultimately, the 2024 Hunt ends up running into Monday morning, one of only a handful of times its taken more than 60 hours to complete. The 2024 Mystery Hunt included what was called the Herc-U-Lease Scavenger Hunt. As part of the scavenger hunt, teams were asked to have as many members as possible look as identical as possible. Death and Mayhem realized that many members were wearing black T-shirts and decided to unify the look with paper hats fashioned from copies of The Tech someone found on campus.MOLLY FREY/DEATH & MAYHEM A little after 5 a.m., team Death and Mayhem solves the final puzzle to win the 2024 Mystery Huntand the responsibility of developing the 2025 Hunt, which kicks off on January 17. In the end, 266 teams have solved at least one of the 2024 Hunts 237 puzzles and Setec Astronomy has solved 174. (Teams typically care less about postgame rankings than about how many puzzles they get to before time runs out.) The Team Formerly Known as the Team to Be Named Later sends out an announcement that a wrap-up event, at which theyll give a full overview of the weekend and hand over the reins to Death and Mayhem, will begin at noon in 26-100. Because creating a Mystery Hunt is such a daunting task, Death and Mayhem got to work on this years within hours of winning, says James Douberley 13, who assumed the title of benevolent dictator to orchestrate and oversee the teams puzzle writing. The weight of expectation is not lost on Douberley and his teammates: This is a once-a-year event that holds a lot of meaning for many participants. The Mystery Hunt is about solving puzzles, but its also far more social and immersive than puzzle books and escape rooms. In 2024, nearly 2,000 people representing 91 teams showed up on campus to participateand another 2,450 or so signed up to puzzle from afar. All told, solvers included 52 faculty members, 278 students, and 950 alumni, ranging from recent graduates to those who got their degrees decades ago. For Chang, the Hunt is an opportunity to connect with the broader community, including alumni from her dorm whom she doesnt see often. This is the one time in the year that we get to all just be in one place together and do this thing that we love, she says. Its just a really great bonding experience. Shortly after solving the final puzzles in the 2024 MIT Mystery Hunt, members of Death & Mayhem received the custom coins awarded to the victors and posed for a photo with Aphrodite (of the Team Formerly Known as the Team to Be Named Later), who blew kisses in celebration.COURTESY OF DEATH & MAYHEM The MIT campus plays a special role in the Hunt. Maybe you have to use the walls of the List Visual Arts Center lobby as a grid for a logic puzzle, or find certain names on the memorial plaques in Lobby 10 whose first letters spell out an answer. But its not just that clues can be part of the physical spaceits that campus is the epicenter for the MIT spirit of creativity, inventiveness, and industriousness that makes the Mystery Hunt unique. People talk about New York being a character in movies, Katz says. I feel like MIT is a character in Mystery Hunt. For Douberley, the Mystery Hunt takes him back to his student days, when he tackled hard challenges through marathon work sessions and all-nighters. You fall asleep on the floor, and youre in the dorm lounge and your friend comes and wakes you up and says, Heres a coffeeI need your help with something, he says. And that is something that lives with you for the rest of your life. Editors Note: The 2025 MIT Mystery Hunt kicks off on January 17, 2025. But if youre eager to start puzzling before thenor get a taste of puzzling if youve never taken part beforecheck out theMIT Mystery Heist, a pre-Hunt round of puzzles written by the Mystery Hunt team known as the Providence Crime Syndication. Learn more and solve atmitmysteryheist.com.