The Necessary Conditions for John H. Watson (2015)

In The Necessary Conditions for John H. Watson (ワトソンの条件), players act as assistants to a famous Victorian detective, competing to uncover clues, secure keys, and bring criminals to justice.

Each round is divided into two phases. During the Plot Phase, players alternately place their action tokens around the edge of the board in a back-and-forth order, carefully positioning them to control future options and deny opponents key spaces.

In the Action Phase, those tokens are moved to adjacent locations to trigger actions. Players can activate character abilities, collect coins, rotate powerful home effects, or acquire detective tiles by paying evidence. Detective tiles provide victory points, evidence bonuses, and—most importantly—colored keys needed to arrest criminals.

Arrests can happen at any time during a player’s action if the required keys are revealed. Capturing an accomplice, the real culprit, or the mastermind grants immediate renown and permanently alters the game state, pushing players closer to victory.

End Game & Winning

The game ends when the Mastermind is arrested (after finishing the round) or when 10 rounds have been completed. Players then total renown from detective tiles and arrests.

The player with the most renown wins. Ties are broken by who arrested the mastermind, then the real culprit, then the accomplice. If still tied, players share the victory.