In ワトソンの条件 ("The Necessary Conditions for John H. Watson"), the players are assistants to a famous Victorian era detective, searching out clues in order to capture criminals. In this anime-styled worker placement game, there are two phases, the plot and action phases. In the plot phase, players place their action tokens one at a time clockwise then counterclockwise. In the action phase, tokens are moved to one of two actions adjacent to the token, possibly taking the action from others. Players will collect clues and money to let gain renown or discover keys, which allow them to catch one of the three criminals at large. The game is over when someone has caught the mastermind, or after 10 rounds. The player with the most renown wins!