Ground Attack - Antony Crawford (Your Spectrum-No.6-Page 72)





Ever had one of those days when your entire world is under threat

from an invading alien fleet? Well, all the other clever inhabitants

have piled into their space vehicles and are hanging around in 

space waiting for the uninvited guests to leave and move on to another

planet. But, having pulled the short straw, you're the only one 

left on the planet and you've been placed in charge of the main 

defence unit - base station Alpha - and it's your task to dissuade the 

aliens from doing too much damage to the cities while they're there.

	Protecting Home World is fairly easy using the strengths of base

station Alpha - all you have to do is to track the alien craft in 

your sights and let them have it with the unlimited supply of laser 

bolts. But time is not on your side! You have a limited period of time 

to obliterate the aliens before you see Home World's precious cities

appear on the horizon and, although deserted of their population,

they do provide huge targets. Once one of the cities has been

bombed, the aliens take off to re-arm themselves in their main 

fleet and another craft is sent down. Your job is to cause them so much

damage that they think of Home World as a bad bet to invade

proper!

	When you first type in the program and RUN it, you will be given

all the instructions for play. The controls used are the '5' key 

to move the sights left and the '8' key to move them right. The '6' 

key is used to fire the lasers. The scoring system is based on the

difficulty level you select - between 20 and 100. As the time 

ticks away, you must home in on the alien craft and destroy it; if you 

let the counter get to zero, you'll see the cities come into sight 

and you may well find them going up in smoke if the craft should hover 

over them. 100 points are awarded for each craft you destroy, plus the

number showing on the counter; should you leave it too long and

the counter starts indicating a minus number, this will be 

deducted from your score. Once three of Home World's cities have been

decimated, the game is over - so make sure your score is high

enough ... or they'll be back!

	This game was selected for publication as much as anything else

for its superb graphics - matching some of the best commercial

packages around. Note the clever use of the FLASH command,

and the way the alien craft split up when you land a laser bolt 

on target. Once you've SAVEd the program to Microdrive or cassette,

you'll find it autoRUNs and after each game you'll be offered the

chance of another. There is also a 'high score' facility - so if 

you like seeing your name in lights, you'd better get your eye in 

quickly.





Line 2          Sets the 'high score' details.



Lines 3-5       Set up the user-defined graphics.



Lines 6-9       Contain the data for the user-defined graphics.



Line 10         Sets the screen attributes, calls the routine at line 4000

to print up the instructions for the game, and asks you to input the

difficulty level required (20 is difficult, 100 is a little bit easier).



Line 20         Draws the display outline.



Lines 21-24     Display the main screen area.



Lines 25-30     Set up the variables and arrays: lf - lives; sc - score; A$

- alien; and tco - the difficulty level (this is reduced as you play the

game).



Line 31         Completes the display by printing the time and score in the

front panel.



Lines 90-92     Decrease the time (co) and if it equals zero (ie. the alien

craft has not been shot yet) this routine prints the Home World cities on

the horizon. Line 92 destructs the cities if the alien craft flies overhead.



Lines 100-116   Read the control keys. You may like to change these to suit

your own tastes, or even to make use of a joystick. For those who do want to

alter these lines, please take a look at line 140 and don't forget to change

the text in the instructions.



Lines 120-400   Monitor the alien ship and check to see if ti has been

destroyed (line 140).



Lines 500-590   This routine makes the alien craft explode into little

pieces if one of your laser bolts hits home.



Lines 900-930   Print the main view through the cockpit window of base

station Alpha.



Lines 1000-1019 Print the planet's surface as it seems to rush underneath

you. It's the clever use of the FLASH command that gives the impression that

you're actually moving.



Lines 1020-1400 Print the base station's dashboard and add a few minor items

of detail to the screen to give it a truly professional look.



Lines 1500-1520 This routine provides a couple of extra touches to the

screen border.



Lines 2001-2010 This routine is called if a city has been destroyed or an

alien craft has been shot down. Line 2001 checks to see if another alien

craft is to start its attack run. Line 2005 checks for the end of the game.



Lines 3010-3070 Move the ship across the screen at random - so you'll have

to be nimble on the '5' and '8' keys if you want to keep the ship in your

sights long enough to blast it!



Lines 4000-4007 Print the title page of the game. By moving the character

set pointer around, the words 'GROUND ATTACK' are made to appear from a bit

pattern. The OUT command produces the 'clicks' which come from the Speccy's

speaker.



Lines 4008-4014 Print the first page of instructions for play and wait for a

key to be pressed.



Lines 4015-4023 Once you've read the first page of instructions and pressed

any key, you'll be presented with the second page.



Lines 4999-5020 The 'end of game' routine. The words 'GAME OVER' are printed

on-screen, and a check for a new 'high score' is made; if you haven't

managed to beat the highest score, you'll be returned to the title page.



Lines 5099-5200 The 'high score' routine. This flashy little piece of code

announces that you've beaten the all-time highest score and invites you to

type in your name. It then returns you to the title page and the promise of

another game.



Lines 9998-9999 This routine allows you to SAVE the program to Microdrive or

cassette. If you don't have an Interface 1 unit connected, omit line 9998.



------------------------------------------------------------------------------

TYPE: Arcade



COMMENT: 





This info file was typed by Jim Grimwood



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