Very much Zork- one of the first PC games I ever played (not including consoles, as I had Colecovision and Atari 2600). When you are in an unlit area without a lamp, you are warned that you might be eaten by a
Grue. If you do anything other than light a lamp or torch, you get eaten by a Grue.
The reason that's now my signature is that I was given a link by a friend recently to
the Inforcom website, which has Zork as a free download! It's great nostalgia, and the benefit is that it looks like I'm doing traceroute or something, so my supervisor doesn't even notice the open command prompt.
Edit: Zork is one series of a pre-RPG game called Interactive Fiction. There were many like it, all text-based. Zork 1,2 &3, Infidel!, and Leather Goddesses of Phobos were all examples. Don't ask about the LGoP- you'll have to look that one up yourself.
Edited, Nov 27th 2006 2:14pm by Wondroustremor