One of the best text adventures ever created, but Infocom released many as difficult (or harder) for PC. I was very pleased that it didn't have too much to do with the book (otherwise it would have been too easy!).
Infocom refuses to take the hint and release ANOTHER text adventure. Quite good, but doesn't have too much to do with the book, and with all text adventures, the parser isn't very forgiving and if you take too long trying to figure out the correct command, or you realise that you forgot to pick something up three hours ago to use now, you die....