'Hunt the Wumpus', as found in More BASIC Computer Games, ported to GNU APL.
A good intro on how to do basic user interaction in GNU APL (and perhaps Dyalog, with some adaptations).
As found on RosettaCode.
For reference, a publication in The Best of Creative Computing, Vol. 1, 1976 gives a good description of the game.
The rules and implementation may not be 100% original according to discussions on RosettaCode, but it's close enough :)
The rules are:
The game is set in a cave that consists of a 20 room labyrinth. Each room is connected to 3 other rooms (the cave is modeled after the vertices of a >dodecahedron). The objective of the player is to find and kill the horrendous beast Wumpus that lurks in the cave.
The player has 5 arrows. If they run out of arrows before killing the Wumpus, the player loses the game.
In the cave there are:
One Wumpus Two giant bats Two bottomless pits If the player enters a room with the Wumpus, he is eaten by it and the game is lost.
If the player enters a room with a bottomless pit, he falls into it and the game is lost.
If the player enters a room with a giant bat, the bat takes him and transports him into a random empty room.
Each turn the player can either walk into an adjacent room or shoot into an adjacent room.
Whenever the player enters a room, he "senses" what happens in adjacent rooms. The messages are:
Nearby Wumpus: "You smell something terrible nearby." Nearby bat: "You hear a rustling." Nearby pit: "You feel a cold wind blowing from a nearby cavern."
When the player shoots, he wins the game if he is shooting in the room with the Wumpus. If he shoots into another room, the Wumpus has a 75% of chance of waking up and moving into an adjacent room: if this is the room with the player, he eats him up and the game is lost.