Sherlock Holmes Solo Mysteries 2: The Black River Emerald (2013)

This is an iOS conversion of Peter Ryan’s 1987 gamebook, initially published by Berkley and Iron Crown Enterprises.  The player makes crime-solving decisions on behalf of American schoolboy David Rogers at Shropshire’s Belton School for boys, trying to clear himself of suspicion in the theft of the titular Amazonian gem by uncovering the real culprit.  This sleuthing is achieved with the help of RPG-style skill checks effected through colliding random die rolls against player stats.