The gamebook genre was at its height in the 1980s. These mystery gamebooks allow the reader to enter the world of Sherlock Holmes, though they don't allow control of Holmes himself – he is merely a character who sometimes shows up during play. Two six-sided dice are used for randomization, and players have the choice of either using a pre-created character or building their own by distributing bonus points between six attributes: Athletics, Artifice, Observation, Intuition, Communication and Scholarship. During play, the reader is frequently prompted to note down codes for clues, deductions and decisions. These codes can then affect the outcomes of subsequent sections. At least nine books were planned for the series, but only seven were released in English; the eighth book, though unreleased in its native tongue, did see publication in translated editions in several countries. The ninth book never saw the light of day in any form.