Zork: The Great Underground Empire

The Good
Great images/descriptions, a huge world to explore, a variety of puzzles ranging from simple to agonizingly difficult, a great text parser, and enough random events to make it replayable.

The Bad
The thief, who had a tendency to steal your items and move things around (even before you could find them, sometimes). Also, the main light source is limited and, unless you plan ahead, you can get yourself irrevocably stuck in the dark. But these are just minor annoyances.

The Bottom Line
Zork I was my first REAL computer game. I originally played it on an old TRS-80 Model III with 4k of RAM. Most of the puzzles were challenging enough to keep my 10-year-old brain busy for hours, and the vivid room descriptions still create detailed images in my mind to this day. This game is truly a timeless classic... it is available as a free download (Infocom officially declared it freeware) from the Unofficial Infocom Homepage (http://www.csd.uwo.ca/Infocom/).