An attempt to achieve a goal "the hard way," by voluntarily adhering to rules that complicate an otherwise simple action (sorting cards, placing an object into a container, etc.).
In games that do not involve an opponent, such as solitaire or jacks, the complication that ensues from your willingness to follow a set of rules serves much the same purpose as a live opponent.
The game-like qualities of interactive fiction typically emerge when the player is forced to deduce, and then apply, the rules that describe a given designer's game world. IF gains much of its game-like qualities from the puzzles which the designer at regular intervals interposes between the player and the plot.
Within the IF community, the fiction between "game" and "story" has expressed itself in discussions of puzzleless IF, the kind of experimental work encouraged by Marnie Parker's IF art show, and conversation-driven stories. By contrast, academics focusing on interactive fiction as a form of narrative have generally tended to downplay the game-like qualities of the genre.
In Cybertext, Aarseth complicates the basic concept of game, noting that in computer games, both the game and its player "exchange and react to each other's messages according to a set of codes. The [computer] game plays the user just as the user plays the game, and there is no message apart from the play." (1997, Johns Hopkins UP: 162).
-- DennisGJerz - 09 Aug 2002