I'm trying to work my way through the Infocom catalog, posting my thoughts on a gaming forum all the while.
I started with Zork I, and I suppose it's easy to give it a hard time. The plot is more than thin--a monofilament of a story. The protagonist, an indeterminate blank slate, reaches a small white house in the midst of a forest. Reading the manual(s) accompanying Zork I, the player is told that the Adventurer wants treasure for themselves. The game will award points for collecting it and placing it in a trophy case.
Why does the Adventurer leave the treasure behind, if they want it so much? What is the significance of the case, unremarkably sitting in an unremarkably abandoned house?
In the course of their treasure hunt, the player-protagonist wanders a rather inorganic funhouse of a map, looking for things to do, solving puzzles until all rooms and treasures are discovered.
One of the means of fast travel, while convenient, has no apparent clues as to its use.
Zork has an expiring light source, though sooner or later an alternative may or may not be found.
There are a whopping three mazes, none of them fun or interesting. The largest and most tedious, called only "Maze," features 12 possible exits from each of its rooms as well as an NPC that picks up and moves dropped items--the Hansel and Gretel approach will not work here. Wise players will swallow their pride and retrieve a map from somewhere. Mapping this monstrosity is in no way worth the trouble.
It's easy to forget that the design of Zork was initially undertaken in order to improve upon ADVENT, which was then the only widely-known game of its kind. I suppose this may be a controversial statement: Zork does, in fact, improve upon ADVENT in almost every meaningful way. It is more technologically sophisticated, running on an engine that eventually evolved into one that is widely used today in contemporary IF. It has a sense of humor. It is, compared with its only competitor at the time, more interactive and more descriptive. The puzzles--the fair ones, at least--are more interesting than those in ADVENT. I have seen essays indicating that ADVENT makes fewer mistakes, but then again there is far less of it to begin with.
The parser at the time was a revelation. In ADVENT, the player DROPs treasures on the floor. In Zork, the player PUTs them in a CONTAINER.
We are lucky that Zork made so many mistakes, thus sparing future efforts the indignity of making them. It was not yet clear what made adventure games fun, but Zork was the first step in figuring that out.
This is not to say that parts of it are not fun. I particularly enjoyed the "bell, book, and candle" and coal mine puzzles.
Zork is worth playing for the sense of context it provides. If its outdated nature annoys, then the invisiclues z-code is legally available at The Infocom Documentation Project, free of charge. I found it satisfying to solve, but I think just looking around is worthwhile for the curious.
I give no rating for Zork. I'm not sure that measuring it against contemporary standards is relevant.
In my effort to get through all of Infocom's games, I have determined that Zork I-III and Deadline are too big to judge. I'll give a rating for Starcross if/when I get there.