DUNGEON OF DESPAIR

by Donald Hughes

from Sinclair User, June 1983



Putting the brains into monster heads



Following our series on Basic programming

Donald Hughes devises ways of building

yourself a game with simple intelligence.



HOW MANY TIMES have you wished you could write adventure programs? How

many times have you started, only to cease an hour later, frustrated

by the awful complexity? If the answer to the second question is too

many times, you are probably approaching the problem from the wrong end.



An adventure game should be split into two parts - the brain and the

adventure.



The brain is the interactive part of the program which communicates

with the adventurer, answers queries, picks up items and drops them.

The adventure can then be rendered into data suitable for the brain.



The brain is a loop, normally large, which uses a READ statement to

take data for the adventure from successive DATA statements. Normally

the brain program will run its course once per adventure location, so

when a location is left, it draws new data from the adventure. Using

such a brain, each adventure location can be stored in one DATA

statement of set format.



You must start by deciding what initial intelligence the brain will

have. I recommend you do not aim for anything more intelligent than

the simple example. The example brain understands only one word at a

time and they must be keywords. If the command given is not a keyword,

the brain is so unreceptive that it proceeds merrily along as if it

had found a keyword. It works, though, and you can write adventures,

using the brain, in two hours.



Starting with a brain similar to the example, you can add keywords

slowly until it is reasonably intelligent, and you can have complex

adventures, but start simply, or you will find yourself trying to

debug a program which does not work far enough for you to find the

bugs, let alone see what is not correct; and it will be back to the

frustrations.



Do not expect your first brain, or the example, to run adventures of a

professional standard; that is not the aim - it is to let anyone

starting on a Spectrum have fun with programs they thought were only

in the realm of professionals.



A simple brain operates in this way. The text of the first location is

read in; the number of items in a room is read in; the items in the

room are read into a string array, then printed-out along with a copy

of the text; the monster in the room is read in, along with its

strength. Logically, before the player



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List of variables used in the program

T$  = text

rc  = number of items in a room

A$  = array of room contents

M$  = monster name

M   = monster strength

W$  = answer to fight/run option

C$  = command word

C   = used in loops

Z   = used in loops

S   = your strength

F$  = answer in fight routine

Y$  = answer in take routine

d$  = answer in drop routine

e$  = exit direction

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may take an item he must defeat the monster. Once the monster is dead,

the brain asks what function is required.



The functions understood are:

Take  - to pick up an item.

Drop  - to drop an item.

Inve  - produces an inventory.

Leave - leaves the room.



Those instructions, combined with an imaginative adventure, are

sufficient to entertain.



The brain then asks a question, depending on the keyword used. For

example, What do you want to take? Type in, e.g. "sword". What do you

wish to drop? Type in, e.g., "coin". If INVE was used, the brain

prints out an inventory.



When LEAVE is typed in, the brain asks in which direction. That is

merely for show as, when a direction is typed in, it PRINTS "you are

going to the next room"; PAUSES for a second; CLEARS the screen; and

RESTARTS THE LOOP, reading in the next portion of DATA.



One of the first improvements to the brain you should make is a way of

flipping through the DATA to find any adventure location, so one can

go N., S., E., W. The example brain suffices without that.



In writing adventures, first examine the listing. The brain is

obvious, lines 95 to 850. Remove the data statements, 1000 to 8000.

Insert your own data, in this form:



1000 DATA "A",X,"B","B","B","M",S



A is text describing the room; X is the number of items in the room

and must be equal to the number of strings following it; B is a

string, an item in the room; M is the name of the monster; S is the

strength of the monster. Should you not want a monster, type in the

DATA positions for M and S "none", 0.



Try typing in the adventure below into your Spectrum and playing it to

see the possibilities, within the limitations, of even a simple brain.

You should have plenty of fun. After that, write your adventure for

it. Real beginners should be very careful when typing in the

adventure; a bug will make itself immediately and annoyingly apparent.



To use the brain on a ZX-81, you will have to circumvent the "who

needs READ statements" problem.



Combat works this way; your strength is S; monster strength is M. In

combat, this operation takes place LET S=S-(M*(RND+1)) which means a

random figure varying between M and nearly M*2 is removed from your

strength in defeating the monster. For different adventures, different

Ss can be given, so only by choosing carefully what to fight can you win.



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SCORE SHEET

Due to the limitations of the brain, here is how to score your

performance in this adventure:

If you cheated with the priests, 0; if you took the heavenly being, 0;

if you died, 0.

You should have with you a sword, bag of coins, box of coins, ruby and

Spectrum - the most valuable item.

If you have all five, excellent; only four, good; only three, fair;

only two, bad; only one - have you not played an adventure game previously?

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