I'm going to review one of the non-canon Zork games, since they're probably less well known. Ladies and Gentlemen, I would like to put forth a game called Enlightenment.
Enlightenment is a game set in the Zork universe and stands as an example of how a game can be simple and short while at the same time being good and challenging. It also stands as a good example of interactive fiction and what can be accomplished in a non-graphical medium.
In Enlightenment, you play a standard adventurer at the very end of a vast, amazing adventure. (Just for fun, ask the game what your full score is by typing FULL. The implied game that you're showing up for the end of must have been quite a treat.) Loaded down with treasures and handy adventuring gear, the gate going back into the dungeon closes forever behind you, but the bridge leading out of the dungeon has a nasty troll standing in your way, a troll that is clearly tougher than anything you can safely handle. The game suggests that the only reasonable strategy within your power to execute would be to turn off your light sources to summon a grue to destroy the troll for you.
Sadly, in your zeal to be the best adventurer possible, you are laden with an astonishing assortment of light sources, many of which seem to be permanent. Your brass lantern's battery is no where near running out, and you bought the model with no light switch. Your sword won't stop glowing as long as there's danger (such as a troll) nearby. Even your backpack seems to be blessed with a friendly, ambient light when you begin the game. There's just never a grue around when you need one, I guess.
The entire game takes place in a single room, so it's definitely small and simple. The deceptively plain environment interacts well with your inventory, so while many of the puzzles are challenging and even infuriating at times, the solutions all make sense once you finally put the pieces together.
There are some very minor complaints to be had, I'm afraid. For the sake of realism, it's possible for the game to become unwinnable once or twice, which is a pet peeve of mine even though I acknowledge it as a necessary evil. My other complaint is that the troll in this game is very different from the previous troll encounter way back in Zork 1. This troll appears to be bigger, stronger and dumber than the axe-wielding sparring partner you had in the first game. Given Enlightenment's masterful use of footnotes, I'd normally expect a hand-waved explanation about this being a different type of troll.
Either way, these are very minor complaints. I'd give Enlightenment a solid A+ and recommend it for anyone who can play games written in Inform.