I just want to add that if you like Zork and other Infocom games, then you *have* to check out the many free text adventure games, or better known as Interactive Fiction games, that people have made and are available for download on the internet. There is a very active community of people making Interactive Fiction, including some Professors who teach it at prestigious colleges.
I've been checking them out and wow, some people have gotten really creative and have taken Infocom-type games to a new level with great story telling and innovative puzzles. Plus there are extensive materials and tools out there to allow you to create IF games. For a general introduction to Interactive Fiction playing, history and creating, check out:
http://en.wikipedia.org/wiki/Interactive_fiction
I'd recommend playing the top games from the various competitions:
http://www.wurb.com/if/award/1 - the annual rec.arts.int-fiction competition
http://www.wurb.com/if/award/3 - XYZZY Awards - the IF version of the Academy awards
Be sure to also download the various interpreters (the program that plays the IF game file) , so you can actually play the games. If you're on a PC, for Inform/Infocom/Z-code games, I'd recommend WinFrotz.
http://www.ifarchive.org/if-archive/infoco...wsFrotz2002.zip
It'll let you play both Inform/Z-code games as well as the original Infocom games.
And for IF games made with TADS, go here
http://tads.org/download.htm and find the executable for your Operating System.
Go here to find games:
BAF"s IF guide
http://www.wurb.com/if/
For some recommended authors, check out games made by Graham Nelson, Emily Short, Adam Cadre, Andrew Plotkins and Nick Montfort, as they seem to be some of the elite writers currently making games. Just do a search for them on the BAF's guide. If you lke horror, especially of the Lovecraft variety. Check out Anchorhead:
http://www.wurb.com/if/game/17
And for Zork lovers, check out the "Zorkian" section on BAF's guide:
http://www.wurb.com/if/genre/19