Adult activity books, which combine puzzles with pop culture and mysteries to solve, have become a publishing phenomenon. Murdoku, with more than 140,000 copies sold in Spain, is leading a booming genre that many associate with digital detox.
It used to be the newsstand crossword, the one you took on the metro or to the dentist's waiting room. Now it's 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.
