Zork was one of the first computer games ever sold. It was an Interactive Fiction game, meaning that the game was built as if the player is inside of a novel, controlling the characters and objects within the novel. The game was developed primarily between the years of 1977-1979. The game was originally written for large main frame systems. In order to allow the game to be played on the much smaller, much less capable computers that most people had in their homes at the time, the game had to be split into three portions. The first such installment of the entire game, called Zork I was released in 1980. The next two installments, Zork II and Zork III were released in 1981 and 1982 respectively.
The impact of Zork
One of the biggest improvements that Zork offered over its predecessors was its improved parser. Colossal Cave, for example, would only accept a maximum of two word commands from the player [LIGHT TORCH, GET BOTTLE]. While Zork, on the other hand, would accept much longer and more complicated commands [KILL TROLL WITH SWORD; PUT NOTE, GOLD, AND SWORD INTO BOX]. This allowed for a much more realistic experience for the player.
Additionally, the game offers an antagonist that moves and behaves independently of the player. This type of thing had not yet been seen in a game like this.
One of the challenges faced by the makers of Zork was that, like today, many different systems existed in people's homes, and in order for a game like this to be a commercial success, it needed to run on as many of those systems as possible, so it would have the broadest possible reach. In order to fix this problem for Zork, and also any additional games, the team developed a virtual platform, called Z-machine, for the games to run on. Once the Z-machine was developed for a system, Zork and all of Infocom's games could run on that system.