a choose-your-own-adventure story or RPG, adapted for a computer; it's minimally dependent on the medium. Myst is a holistic experience that could only be accomplished via the video game medium." I claim that Zork is *deeply* dependent on its medium, and in a way that is structurally similar to Myst and its medium. To wit: it is necessary to approach the game world by imagining yourself *in* the game world. You cannot treat it as a state machine rendered in letters (for Zork) or pixels (for Myst). If you try, you'll flail around forever without making progress. (That said, there *is* a narrative quality which Zork doesn't satisfy very well: characters and a story. Okay, there's the Thief, but he's no Mercutio. Mostly it's you, a blank outline of a treasure-hunter; at the end of the game you have (1) acquired treasure and (2) opened a door which leads to more treasure in the sequel. But of course Infocom began covering this territory almost immediately. Zork 3, Deadline, and Starcross were all full-fledged interactive narratives, in their various ways.) So how is this desirable state of engagement accomplished? By giving the player a set of commands -- a range of interactive choice -- which is neither completely arbitrary nor completely laid out for you. (CYOA games (and books) fall at the "fully-defined" end of the spectrum. The arbitrary end is inhabited by, well, by *bad* adventure games -- the ones in which you have to guess words at random until