its the very first text based game, it was released in 1976 by one of the fathers of the internet, Will Crowther, he relesed it for the PDP-10 mainframe computer. In the game, the player explores a cave system rumored to be filled with treasure and gold. The game is composed of dozens of areas, and the player moves between these areas and interacts with objects in them by typing one- or two-word commands which are interpreted by the game's natural language input system. The program acts as a narrator, describing the player's location and the results of the player's attempted actions. It is the first well-known example of interactive fiction, as well as the first well-known adventure game, for which it was also the namesake.