They add time limitations to the Infocom formula and also introduced us to Sgt. Duffy, who is still referred to occasionally by old-timers in adventuring. Deadline is in the classic locked room genre and places a time limit on finding the murderer. Witness is set in 1938 Los Angeles, and is my favourite of the trio. It, too, allows you only twelve hours to solve the crime.
Suspect takes place at an uppercrust estate, where a costume ball turns deadly.
Ballyhoo puts you behind the scenes in a circus where the owner's daughter has been kidnapped. Moonmist covers yet another genre, the gothic romance. Set in a prototypical English castle that may or may not be haunted, it rounds out the collection of mysteries nicely. In some fit of obsession, I played through all of Infidel in a single weekend. I think I may have slept for a couple of hours, but I can't remember for certain.