Adult activity books, blending puzzles with pop culture and mysteries to solve, have become a publishing phenomenon. Murdoku, with more than 140,000 copies sold in Spain, leads a booming genre that many associate with digital detox.
It used to be the newsstand crossword, the one you took on the metro or into the dentist’s waiting room. Now it is a purple-covered notebook with the outline of a house drawn as a sudoku grid, or a hardback packed with questions about Rosalía and Netflix series.
Adult activity books, the latest mutation of the classic pastime, have become a publishing phenomenon that is no longer confined to summer, and within it there is a subgenre that is eating up all the rest: solving a murder armed with a pencil, an eraser and a sudoku grid.
The trend began a decade ago with colouring books aimed at adults, sold under labels such as art therapy or anti-stress, featuring mandalas, flowers and landscapes. What looked like a summer fad took root, and from there a more ambitious version emerged: the adult activity book, an update of the traditional newsstand puzzle book (crosswords, word searches, sudokus) with an extra ingredient that sets it apart: popular culture.
The arrival of the mobile phone did not kill off the analogue genre; instead, the two now coexist, just as YouTube cookery channels have not sunk recipe books, or television did not kill radio.
Blackie Books and its distinctive activity books
Blackie Books was among the first to spot the potential. Its adult activity books are already on their 14th volume, one per summer, and have passed 250,000 copies sold, according to the publisher’s own figures. The latest offers 60 exercises on music, film, TV series, literature, science and sport, designed to “de-rust the mind”.
Success has led the publisher to branch out the concept: the “Cuaderno Kids”, for children from the age of six; the “Cuaderno Golden”, aimed at older readers with memory challenges and questions about well-known faces from years gone by; and the “Quadern”, its Catalan-language version, with local touchstones such as Mercè Rodoreda or the castellers.
Other imprints have carved out their own niche without resorting to crime: Debate has launched an activity book signed by “El Mundo Today” that tests the ability to distinguish reality from fiction, and GeoPlaneta is already on the fifth volume of a travel activity book, complete with playlists and gastronomic guides.
Murdoku, the hit that has fuelled the craze for solving crimes
If one single book sums up the season, it is Murdoku. The notebook, with its unmistakable purple cover, has already sold more than 140,000 copies in Spain, and this year it has flown off tables at several spring book fairs. Its mechanics reinvent the classic sudoku: each puzzle places a group of suspects in the squares of a grid, without repeating any of them in a given row or column, and the square that remains empty shows where the victim is; the suspect whose position matches that square is the killer.
The difficulty increases as the book progresses, to the point that some bookshops are now organising live solving competitions. Behind it is Canadian Manuel Garand, a puzzle designer based in Montreal whose work has also been published in the “Financial Times”.
Such is the success the book has enjoyed (and that of those trying to imitate it) that other people have even set up a website with the same concept where you can tackle Murdokus for free. At the time of writing there are 35 puzzles to complete, and that is with the site still in development.
Murdle, Agatha Christie and the rest of the crime genre
The other big name in the genre is Murdle. “Resuelve el crimen” (published in Spain, like “Murdoku”, by Temas de Hoy), uses a different mechanism: instead of a sudoku grid, it offers narrative clues about suspects, weapons and settings that you have to cross-reference to point to the culprit.
It already runs to three volumes and a children’s edition; its creator, the American G.T. Karber, started by publishing a case a day online before becoming a print bestseller. Espasa has followed suit with “Los casos de Agatha Christie: 100 acertijos y un misterio por resolver”, the first official activity book about the British writer, which invites readers to step into the shoes of Poirot or Miss Marple.
And there is more: “El crimen del verano” takes the genre to the beach and poolside, with 121 suspects and clues scattered across sudokus, crosswords and number pyramids; “Crimigramas”, meanwhile, hides the killer inside word searches. None of these formats is new on its own, but when combined with a mystery plot they make sure the reader stops being a passive spectator and becomes, puzzle by puzzle, a detective.
Another way to switch off from your phone?
Behind this craze for paper and pencil there also lurks a weariness with screens. It is no coincidence that more and more of these books are being sold explicitly as a way to disconnect from the digital world, with no notifications and no rush, designed to reclaim that bit of leisure time that used to be swallowed by the mobile phone.
On top of that comes a more practical argument: those who follow the phenomenon closely point out that this kind of game works attention, memory and cognitive flexibility, although there is still no study to confirm exactly what lies behind their success.
No one expects a paper pastime to compete with the sophistication of a video game; in fact, that is not the aim. It is more about a different niche: a few minutes with the mind occupied and no screen involved, something that more and more people are seeking as part of the pastime itself.