[wduquette]

We had a copy of the Fortran source for the PDP-11 when I was a teenager. My buddy and I managed to add a room: in the first room of the Maze of Twisty Little Passages All The Same, if you gave the command "out" (as one tried), you discovered that you were "Nowhere". "There is nothing in all directions." You could then enter "in" to go back to the Maze, or "get nothing" to add "nothing" to your inventory.

There was a place in another room where your way was blocked by lava; our plan was to let you drop the "nothing" on the lava, and proceed, but we had run out of memory. (28K max!)

[quuxplusone]

Are you talking about the Volcano View? ("You are on the edge of a breath-taking view. Far below you is an active volcano, from which great gouts of molten lava come surging out, cascading back down into the depths. The glowing rock fills the farthest reaches of the cavern with a blood-red glare...")

Or did you and your friend also add the lava room? Or (this would be the really interesting case, family-tree-wise) was there already a lava room present in your version?

I can't immediately think of a lava obstacle in any version. (Well, the volcanic rift in GOET0580 and IIRC the very endgame of ROBE0665, in a sense. And the Volcano View is crossable in PLAT0550 and its descendants.)

Infocom's "Hitchhiker's Guide to the Galaxy" (1984) includes an object named "no tea", which is in your inventory for much of the game.

[wduquette]

Yes, the Volcano View. We planned to add a new area just past it, but as I say we ran out of memory.

I've no idea where the version we started with would fall in the family tree, but this would have been ~1979, and the OS was HT-11, Heathkit's version of RT-11 for their H11 computer kit. So far as I know there was nothing special about it, except that it had been ported to RT-11 on the PDP-11.