ALIEN RAID
by Julian Henschke
from Popular Computing Weekly, 16th August 1984

Pit your wits and reflexes against a bizarre array of mutants in
Julian Henschke's game for the 48K Spectrum.


This is an arcade-style game for the 48K Spectrum, in which you must
protect your central life-support command base from attack. Various
weird and wonderful aliens are seeking to destroy the base, including
octopi, streamers, swarmers, bombers and a large cast of mutants.

Any aliens which escape your fire range will plant a time bomb at the
base. Ten time bombs are enough to destroy the base.

The biggest danger is the Super Zapper, which may raid at any time
with probable fatal consequences. Your only hope is to hit the
computer-assisted auto-zap button (H) which will immediately destroy it.

Take care when typing in the DATA statements, as some machine code
is included.


Variables
ay,ax           alien's y,x co-ordinates
sc              current score
hi              highest score
bonus           bonus awarded for completing all five waves
land            number of aliens landed
a               current alien type
c               number of aliens remaining in current wave
m               alien's random movement up/down
s               score awarded for current alien
i               INK colour of alien
l               executes machine code
PEEK 23300      your x co-ordinate
PEEK 23301      your y co-ordinate


Program notes
1-2             set up game
100-200         main loop
400-440         firing routine
450-455         sound routine
500-510         "Do you want instructions?" and start game
600             sets up variables
700-795         instructions
800-810         alien landing routine
900-999         graphics / machine code (key scan/print)
1000-1060       sets up screen
1500-1530       base destroyed / end routine
1700            restart game
