Sherlock Holmes is the main playable character with Dr.John Watson, Toby and Constable Marrow playable briefly. The majority of the game involves exploring crime scenes and examining clues. Once discovered, clues are added to a "deduction board," a gameplay mechanic which involves linking pieces of information together. It will lead to possible different deductions. Once deductions are connected together, player will have a full tree of deductions. (wikipedia.org).