Zork (1-3) Free download, for Windows and Macs
Then download the PC versions. Extract them all to one folder, (I did it in ~/zork). Then mount that folder as a drive in dosbox. (ex. mount c ~/zork)
Or on OSX, use Zoom http://www.logicalshift.demon.co..../zoom.html.
Download and install Zoom. Download the PC version of zork(1,2,or 3), rename Data/Zork1.dat to Data/Zork1.z8 . Double click Zork1.z8.
Dosbox is needed on x64 versions of Windows as well (such as Vista x64).