Infocom/Inform Text Adventures on the QL
By Tim Swenson
In the Beginning
"It is a dark and stormy night. Lightening illuminates the room
you are in. Briefly, as the lightening flashed, you can see that
you are in a large library that seems to be part of a castle.
The room is full of books stacked on the shelves and everywhere
else. One the table before you is a parchment scroll, a candle,
and a match."
This is the start of a text adventure game. In the late 70's,
Will Crowther and Don Woods created the first popular text
adventure game, "Adventure." Scott Adams picked up the idea and
wrote a number of successfull adventure games for the TRS-80
computer. Sierra Games picked up the style, added some graphics,
and wrote text adventures for the Apple II. "The Quill" was a
system used on Spectrums to make many commercial text adventure
games. It was Infocom that took the text adventure to a higher
level.
Infocom developed a system that made the game in two parts, an
Interpreter and a game data file. Since the user interaction
part of each game was the same, Infocom created an interpreter
that could be used with all of their games. The game was stored
in the game file (in a "Z-Code" format) and read by the
interpreter. To cover a number of different computer platforms
all they had to port was the interpreter. The game data files
did not have to be altered but could be used on any platform.
Infocom was able to create games for MS-DOS, CP/M, Apple II,
C-64, and other platforms.
The Infocom game format was so popular that people started
copying it for thier own purposes. Mark Howell wrote a Z-Code
interpreter called "ZIP" (not to be confused with the archive
utility of the same name). To create the games, Graham Nelson
wrote "Inform" a compiler of Z-Code games. It uses a C-like
language to write the text adventure games. Many enthusiasts of
text adventure games ( or "Interactive Fiction" as it as also
called) have used Inform to create their own games. There is
even a yearly competition for writers of Interactive Fiction.
These two utilities have been ported to many computer systems,
including the QL. Luke Roberts has ported both ZIP and Inform to
the QL, letting QLers both develop and play text games.
ZIP
There is not much to say about ZIP except to say that it works.
The original distribution from Luke Roberts comes with two games
to get you started.
exec zip;"curses_dat"
This is all it takes to start playing. From this point you have
an angle backet prompt for entering your commands into the game.
The games come with few instructions and you are supposed to
puzzle it out for yourself. In fact, the whole idea of adventure
games is to figure out the puzzle.
ZIP also comes with a few utilities to "assist" your play (read
that as "cheat"). Infodump extracts information from the game
data file, allowing you to see inside the game. Txd is an Inform
disassembler that turns a data file into a Z-Code file. You have
to know Z-Code to really use Txd.
INFORM
If you actually have the interest in developing text adventures,
Inform is the system that lets you do it. Inform uses a language
fairly similar to C letting you be fairly expressive about how
you want the game to run. Inform compiles the source code and
creates a Z-Code file that is then used by ZIP. Since Z-Code
files are portable, any adventure that you create on the QL can
also be used on any other platform that has ZIP. Inform comes
with a fair amount of documenation and a number of source code
example games. Since Inform is a language, you will have to put
for some effort to really develop a game. It is powerfull but
trivial to learn.
Inform comes with a couple sample adventure files (_inf). The
sites listed below also have a number _inf files. These can be
compiled to the resulting game file or you can study them to see
how the games were made.
The Games
Now we come to the key point. I've sure that there are not many
QLers interested enough in text adventures to write games for
other QLers. But, since the game files are portable we can use
the games written for the other platorms.
I was able to find a few key sites on the Web that store Inform
games. These sites are:
Snacky Pete's Text Adventure Archive
http://www.helikon.com/Personal/Pete/Advents/iflib.htm
Inform Programming
http://www.cl.cam.ac.uk/users/gdr11/inform/
Combined, there are about 30 games available. The second site
has a number of example Inform files that show how various
actions are done in Inform. A version of the original Adventure
is available, along with: Adventureland (by Scott Adams), Paper
Chase (the object is to get a college degree), Detective (using
the characters from "Mystery Science Theatre 3000"), Odieus's
Quest for the Magic Flingshot, Busted! ("a game of high cunning
and low humor"), and others. Some games are small (43K) and
other go as high as 224K. I'm assuming the larger the game file
the bigger and more complex the game.
If you visit the Activision home page, they are giving away a
free copy of Zork I, the most famous Infocom game. They are
giving away the MS-DOS version, but you can copy the ZORK1_DAT
file to the QL.
I've downloaded a few of the games (including Zork I) on these
pages to make sure that they will run on the QL. Z-Code came in
different versions, with version 3 and 5 being the most popular
and these are supported on the QL version of ZIP. There are some
games written in version 7 and 8, but these games will not run on
the QL.
There are even a few e-zines that support text advetures. XYZZY
News and SPAG Newsletter (Society for the Preservation of
Adventure Games) are both available via the Web (use Yahoo or
Lycos to find them). Both of these newsletters have fairly
current issues, meaning that there are still people out there
writing Inform text adventure games.
Having ZIP ported to the QL means that we can take advantage
their efforts and play these games ourselves.
The Files
Both Inform and ZIP may be available on a QL BBS near you. For
North American QLers, they are available on QBOX USA and from QHJ
Freeware (me) at the address below. They were available on
maya.dei.unipd.it, but I think it had a disk crash. You should
still find them on one of the mirror sites, like ftp.nvg.unit.no.
QHJ Freeware
c/o Tim Swenson
5615 Botkins Rd, Huber Heights, OH 45424
swensont@mail.serve.com http://www.serve.com/swensont/