Sleuth is a text-based "whodunit" computer-game created by Eric N. Miller of Norland Software and released in 1983.
When the game starts, a murder has just been committed. The object of the game is to solve the murder by examining the house and talking to its occupants. Being a text-based game, the graphics are simple and consist of ASCII characters. The user moves the character with the arrow keys, and interacts with persons and objects by issuing commands (from a limited vocabulary list) at the game's prompt (similar to Sierra's "Quest" games). To win, the player must accurately identify the murder weapon, murder location, and the murderer. The player can do this by examining different objects in the game, talking to the occupants and observing their behavior. The murderer is the one whose alibi contradicts everyone else's.
The game is made challenging by the fact that the player has to keep track of everyone's stories and also can only question people once or twice before the murderer becomes suspicious. If the player takes too long to solve the mystery, the murderer will eventually kill the player's character and the game ends.
The game has two modes: a "Basic" mode and a "Personalized" mode. The only difference between the two modes is in the naming of in-game characters. In "Basic" mode, the game randomly generates the name of the characters, whereas in "Personalized" mode, the player can supply the names of the characters. Although the game is simple, no two murder scenarios are exactly alike as the game randomizes attributes of the game like the victim, murder scene, murder weapon, and murderer.
Source: Wikipedia, "http://en.wikipedia.org/wiki/Sleuth_(video_game)," available under the CC-BY-SA License.