Brenda Laurel takes a turn at the rules of operation for Interactive Fiction.
In my view, Nick Montfort's most important observation is that computer games are a new kind of animal that comes in lots of different sizes, colors, and subspecies. His observation that a computer game "is a potential narrative that may contain game elements" points to a reader-response-oriented view, that the narrative can be understood to be the player's construction of what happens in an interactive session.
Montfort asks why we use the word "game" as a default noun, when clearly many forms of interactive play are not games. It may be because "game" approximates the idea of "play," which, when used as a verb, often takes "game" as its object. But the central pleasure of play, as for the audience member of a theatrical event or for the reader of fiction, depends upon the absence of serious consequences in real life. We can feel for Hamlet but we will not die with him.
What experts call "play patterns" in children's play are instructive in figuring out the structure of play with computers. "Games" are forms of rule-based play. Playing with pattern and rhythm (as with clapping and jumping games) may illuminate the underlying play pattern of games such as Tetris or Breakout. Equally attractive to kids is exploratory or "free" play, where the underlying play pattern often involves improvisational story making. Narrative construction as a play pattern provides an excellent starting place for understanding the pleasure that is particular to IF.