Before we get into the game itself, you should know that you can download Zork for free from Infocom's download page. So feel free to boot it up and take a ride back to the 1980s with this masterpiece.
Zork is an interactive, text-based computer game originally released in 1980. This series, split into three separate games, introduced a robust and sophisticated text parser to gamers. People were largely used to the simple commands used in the popular game Colossal Cave Adventure, but Zork allowed users to send more complex commands that included prepositions and conjunctions.
Zork tracks your score as you explore the map, find tools, and collect trophy items (e.g. a jewel-encrusted egg). When you place your trophy items in the trophy case found in the Living Room area, you gain score points. Collecting the Twenty Treasures of Zork and placing them within the trophy case wins the game. However, you must explore the map, solve puzzles, and avoid being eaten by a grue to collect these treasures.
Since Zork is a vast and complex game, it helps to have a map as you explore and collect your trophies. However, if you want to play the game as it was truly intended, you should try to play it without using the map.
After playing the game (for the first time ever) for several weeks around 2014, I was finally able to beat the game with some online help finding the last couple items. As I was writing this post, I installed the game again to grab some screenshots to show off the true glory of this game. As noted in Jimmy Maher's playthrough, the original Zork games looked quite a bit different due to the older hardware of computers like the Apple II and multiple bug fixes that Infocom pushed out after the game's initial release. My playthrough uses the Zork Anthology version, which utilizes DOSBox on Windows.
The first screenshot here shows the introductory information, which doesn't include instructions of any kind for the player. If you haven't played text adventures before, try to use simple commands like "go west", "look around", or "hit troll with elvish sword".
In this second screenshot, we see the player has entered the house and found the trophy case in the living room. The lantern and sword in this room allow the player to explore dark areas and attack enemies. If you don't use the lantern, you won't be able to see anything in dark areas and you may be eaten by a grue.
Finally, we see that the player has found the first treasure: a jewel-encrusted egg. These treasures can be taken back to the house and placed in the trophy case or carried until you feel like you want to put things away.
It's been quite a few years since I first played Zork, but I clearly remember the late nights and bloodshot eyes that helped me find all the treasures. This game is well worth the time and effort, even though the text-based aspect may be off-putting to gamers who didn't have to grow up playing games without graphics. However, I believe that the strategy and skills learned in early video games like Zork can actually help you even when playing newer games.
If you do decide to play Zork, you can download Zork I, II, and III from Infocom's download page for free or search the internet for an online version.