Deadline (1982), a murder mystery by Marc Blank.
As described on the box:
It's been called "part of the latest craze in home computing" (TIME magazine), an "amazing feat of programming" (THE NEW YORK TIMES) and the "Best Adventure of 1983" (ELECTRONIC GAMES).
It's DEADLINE, and it pits you, the keen-eyed sleuth, against a 12-hour time limit to solve a classic locked-door mystery. Armed only with the clues inside this package and your own wits, you must sift through myriads of evidence and motives to track down the killer. No easy feat, for all six of your suspects exercise free will -- coming and going, scheming and maneuvering 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.