Deadline (Infocom from Mastertronic)

Twelve hours to solve the mystery. One false move, and the killer strikes again.

Deadline pits you, the chief of detectives, against a 12 hour time limit in this classic locked door mystery. A wealthy industrialist is dead of a drug overdose and you've been called in to determine whether it's suicide or murder. To learn whodunnit you must sift through a myriad of clues and motives. No easy feat, for all six of your suspects exercise free will -- coming and going, scheming and manoeuvering independently of your actions. And some of these personalities are so treacherous that, should you make the wrong move, one of them may do you in.

For real diehards, seeking the ultimate challenge in interactive fiction.

Deadline Manual