Interactivity is similar to the degree of responsiveness, and is examined as a communication process in which each message is related to the previous messages exchanged, and to the relation of those messages to the messages preceding them. (Wikipedia)
Interactivity to me from reading this source taken from Wikipedia, and reading other sources is essentially a relation between messages given and their “interactions” with each other. Indeed Zork and Cup of Death are both examples of interactivity, and can be considered interactive narratives. Narratives tell a story or recount past events, Zork and Cup of Death both offer this and because they both require input from the user I would consider them a form of an interactive narrative. I can see why some people would view an interactive narrative to be impossibility because the narrative itself is constantly changing and can take many different routes and even end differently. Yet this is the way most movies are presented and they too are considered narratives so why not consider an interactive story within some parameters a narrative? So with that said I can say that adding interactivity to a narrative makes it more fun for me to read and experience. With Zork it was like I was there I could envision myself in front of the house (which I spent about 20minutes trying to get in), finding a little golden egg in a nest and hearing the bird nearby (though I have yet to find it). It made me think of the parameters of the story and the context in which it was taking place. I was forced into creating a little dungeon map and a map of the simulated world like most video games give you. The interactivity indeed keeps this story interesting and it was at times sort of aggravating because I felt the story was already written and I was missing something. I didn’t get this from reading Cup of Death where the story was meant to flow no matter what choice I made. In Zork the story was given in spurts where I learned of certain things where I went along which is typical of most narratives but in this case I got a little bit at a time rather than finishing the narrative in order. I felt like I was playing Clue or something. It really adds an “adventure” to the text and allows u to almost enter the narrative. If I ever finish Zork (if there is an end) I’m sure that it will all come together but with most role playing games or choose your own adventures there will always be the what if factor. So this interactivity always leaves me with questions like what is this egg used for, or why can’t I find this bird. Similar cases are in Cup of Death but they come together because the story is written and cannot be changed so it answers the questions for you in your own interactive narrative. I cannot envision Zork being very interesting without controlling it myself, it seems to compare to books like “see spot run” when taken out of context. When interaction is added it brings excitement to the story that otherwise would not be there.