GROUND ATTACK
from Home Computing Weekly, 13th September 1983

Buck's turned nasty - he's out to flatten your city.

Buck Rodgers seems to have gone over to the enemy. Type Sandy MacLennan's
program into your Spectrum quickly, before innocent cities are blasted out of
existence.


Ground Attack is for everyone who can't stand Buck Rodgers  now you have a
chance to shoot him down.

After you have chosen your time  displayed in a panel  a city becomes
visib1e and Buck will start his run from the top of the screen. He might not
be visible at this stage, but when his attack begins the time will start to
count down and target lines will appear.

Buck moves randomly across the screen, but you can bring him into your line
of fire by using the right and left cursor keys. Your fire button is the down
cursor key. Every time you destroy Buck your start time is reduced by one. If
you manage this within 10 per cent of your time then your time for the next
game is halved.

Each destroyed craft earns you 100 points, plus the unused amount of time. A
negative time is deducted from your score. When your time is down to 25 you
will gain an extra man and this will be identified by a BEEP.

Although the program is written entirely in BASIC, it runs relatively fast
because only that which must move does so. The ground uses black and yellow
bands of varying thicknesses which flash alternately to simulate perspective.

It is possible for Buck's craft to leave your line of sight, achieved by A$
which is 44 characters long and is always printed at one space in from the
side and the number of characters displayed is determined by the right and
left cursor keys and by the random factor z. This allows the craft, or part
of the craft, to be displayed anywhere along the line of movement.

To make the game more tricky, just reduce the figure 0.9 in line 2002. You
could also add another enemy spacecraft. The user-defined graphics: A-D enemy
spacecraft, E bars for ground, F-H the city, I and J triangular segments, K
and L laser bolts.


How it works
   3-9     set up user defined graphics
  10       screen colours, GOSUB for logo, ask for time, set score
  25-30    set up score, draw and randomize enemy
  31       print score, time
  90-140   main program: movement of enemy, check for enemy position, time,
           print cities, decrement time
 500-590   enemy explosion routine
 900-930   screen details
1000-1400  flashing ground
1500-1506  screen details
1511-1520  target sight
2000-2010  check if time equals 25 for extra life
3000-3070  controls flight of enemy
4000-4007  logo


Variables
tco   start time
co    current time
sc    score
a$    spacecraft
x     start of a$
px    end of a$
lf    lives total
y     lines from top
z     random factor

