

ASTEROIDS AHEAD!

by Clyde Bish

from ZX Computing Apr/May.1983



Steer your spacecraft clear of the asteroids

in this exciting game from Mr. Bish of Exeter.





There you are, a lonely spaceship floating through space,

when suddenly your peace is shattered by a swarm of

asteroids bearing down on you at a great rate of knots. You

can manoeuvre your craft left using the '5' key or right

with the '8' key. You also possess an energy field which you

can use to deflect asteroids you cannot avoid, but beware of

running out of energy - the energy field has only a limited

strength and a short range.



User defined graphics have been used in this program for the

asteroids, the energy screen, the spacecraft and the

explosions. They are set during the initial display, thus

not causing an embarrassing pause during the game.



Logic lines have been used within the program. The most

well-known example of these are present in line 50, but you

may like to study the less popular conditional GO TO used in

line 405. Also, the use of ATTR to detect the presence of a

white asteroid in the path of the yellow spacecraft should

be noted; SCREEN$ (x,y) would not work with user defined

graphics.



Line 460, which goes to itself, is used to prevent a STOP

message from spoiling the appearance of the screen. Press

the Break key to stop the vicious circle.



It should also be noted that the capital letters within

quotes in lines 62, 100 and 400 are user defined graphics

and as such should be entered in Graphics mode.



The program is also equipped with a routine to give your

score and the best score achieved, and there is also a

best-ever score with the initials of the player who managed

to build up that score. To operate the best-ever score

option, enter:

	LET e=0

as a command, and then SAVE using:

	GO TO 430

The program, when LOADed, will GO TO line 1 and execute

itself, complete with variables.





--

Another Fine Product transcribed by:

Jim Grimwood (jimg@globalnet.co.uk), Weardale, England

--

