Well, that depends on the level of detail. From what you write below,
it seems as if you want to use not just the universe, but specific
characters, like Belboz. That would probably be copyright infingement,
yes.
On the other hand, what you're planning to do sounds like a pastiche
or parody rather than outright plagiarism. What parody authors tend to
do to saty out of legal trouble is to change names etc. slightly. For
example, if you were writing about "Zark" and "The Wizard of Foobar"
rather than Zork and the wWizrd of Frobozz everybody would still
recognize them, but you would probably stay out of trouble.
>If I don't charge money and make it "freeware", is there still trouble?
Yes. What matters in civil law is not only what you make out of it,
but the damages you cause. In principle, you could write something
(very different from what you're planning, of course) that didn't earn
you a nickle but that cause enormous damages to somebody else.
>And if not, how could I make the appropriate messages? Can I have
>one blanket statement , "Zork, Belboz, frotz ... are copyrights of Infocom.."
>or would it have to be referenced every tep of the way, "You say 'hello
>sailor(tm)' to Belboz(tm) who gives you the frotz(tm) spell."
You're confusing trademarks and copyrights here.
The names of characters in literature aren't normally trademarks
(unless specifically registered as such; I suppose "Zork" might be a
trademark of Infocom's). Attributing the names to their "owner" is not
considered enough.
Magnus