BBC - Radio 4 - The Hitchhiker's Guide to the Galaxy - The Adventure Game
From their website:
Based on the popular radio and book series, "The Hitchhiker's Guide to the Galaxy" is a text-based adventure game, considered by many to be a classic.
The plot of the game roughly follows the first book, starting with the destruction of the planet earth and ending with the gang landing on the "lost" planet of Magrethea.
This has to be done in a very roundabout way, by collecting various tools and several different kinds of pocket fluff(lint). The game also has you assume the roles of other characters in the story line, leading players to use the "Who am i" command to find out who they are playing as. It also has an in-game version of The Hitchhikers Guide To The Galaxy, which you can consult for information on numerous topics in the book/game universe.
Taken from: http://www.giantbomb.com/the-hitchhikers-guide-to-the-galaxy/61-11797/
So sit down brew a pot of coffee, and try solve the problems...