The Invasion

Mars had been watching the planet Earth for centuries, and saw

it slowly destroyed by its own inhabitants. The few surviving

Humans fled into space, determined to occupy the Solar System's

last habitable planet. With an invasion imminant, the Martians

built a powerful weapon to defend the red planet, vowing the

invaders would never reach the surface.

Getting Started

Following reset a title screen is shown until you press a key

from 1-6 on keyboard A to select a game (see Table 1). The

object is to destroy the incoming UFO formations with your laser

cannon. There are eight unique waves to deal with.

Controls

The game uses keyboard A only. Keys "2" and "6" move the laser

cannon left or right along the bottom of the screen. Press "5"

to fire the laser cannon. You can't fire again unless you hit a

UFO or the missile travels off the screen (see Section 3.4).

Press the console's reset button for a new game.

Scoring and Lives

Your score is shown by the left numeric display. Each UFO hit

with a missile increases the score by one point. The highest

score that can be displayed is 255 - the next point after this

causes a rollover to zero.

You don't score if your laser cannon crashes into a UFO, but you

do lose a life. The number of lives you have is shown by the

right numeric display. You begin with three lives, so you can

only afford to be hit twice. If you are hit a third time you

are permanently eliminated and the game is over.

Game Variations

Choosing a game is done on the title screen by pressing a digit

from 1-6 on keyboard A. Difficulty increases every eighth wave

with an increasingly slow response to player movement controls.

Beginners have the option of starting with a relatively quick

response time for their first eight waves.

Only one missile can be in play at a time. In regular games it

will explode on contact with an enemy, and you can fire again

immediately. Indestructible missiles must travel off the screen

before you can fire again. While you can hit several enemies

with one shot, missing a nearby target can be fatal.

Press 'Clear'. On Keypad A choose game (1-6) '1' (easiest) to '6' (hardest). Controls are '4' (left), '6' (right), '5' (fire)