Stargate/Gameplay

Controls

 * Joystick: This maneuvers your Spaceship up or down--not across. You can safely move anywhere on the screen, even below the earth's surface.
 * Thrust: This control moves you forward at whatever pace you desire. If held down, you'll accelerate to top speed. If left alone, you'll stop.
 * Fire: You have an unlimited amount of fire. Your laser fires all the way across the visible screen.
 * Reverse: Use Reverse to eliminate the Landers as fast as possible, as keyed by the Scanner. Reverse is also useful in killing Mutants.
 * Hyperspace: Hyperspace makes your Spaceship disappear and reappear--anywhere. You have no control over where you'll end up. One use for Hyperspace is when the Baiters appear or when your world has blown up.
 * Smart Bombs: You begin with three of these, and earn a new one every 10,000 points. Smart Bombs destroy everything on the screen. Use them only after you've scored 30,000 points, and then only when you need to. For example, when Mother Ships appear in a group, blast them senseless with the Smart Bomb.
 * Inviso: The Inviso cloaking device makes your ship impervious to attack. While Inviso is active, any enemy that touches you is destroyed, but you have a limited supply. Make sure you are safe before letting go of the button or running out of Inviso.
 * 1-Player: Press to start a one player game.
 * 2-Player: Press to start a two player game.

Spaceship
This brighly glowing craft is the Defender. You command this Spaceship over and under the Earth's surface. It travels horizontally on your screen in either direction. You can progress through the atmosphere at the speed you choose. The joystick determines its flight altitude. Constant pressure on the Thrust button will result in constant accerelation. You have an unlimites source of Laser fire. You can reverse and you can instantly Hyperspace to another part of the world at will.

Humanoids
These colorful stick figures are the Defendees. Humanoids are peaceful while they're still human. They often walk around the Earth's surface in groups. Don't shoot them. Protect them. Their role in the space battle is a passive one, unless they are successfully kidnapped by Landers and carried to the top of the screen, where they become Mutants. If allowed to mutate, you've got one big problem on your hands. Although you should try to catch every Humanoid that you rescue from a Lander, they can survive short falls back to the surface.

Landers
150 points. You must destroy all the Landers on a screen to complete an attack wave. A Lander's basic objective is to grab Humanoids and carry them to the top. They warp into the atmosphere, and begin to hover over the Earth's surface in search of a Humanoid that they can lock their tractor beam on to. They will fire at you, but not aggressively. You can easily avoid their fire. They usually appear in groups of four or five.

Mutants
150 points. These are formed when a Lander successfully carries a Humanoid to the top of the screen. The Lander then sucks the Humanoid into its body and combines genetic material from the two lifeforms to become a Mutant. These are dangerous. Their main objective is to kill you, and the never shoot straight, always at an angle. If a Mutant appears, muster all your energy to kill it. If the Landers carry all of your Humanoids to the top of the screen, and all of your Humanoids become Mutants, the world as you know it will explode. This is no pretty sight, and nearly impossible to stay alive in. Some advice: Don't let the world blow up.

Baiters
200 points. These enlongates ships can shoot faster and fly faster than your Spaceship. Baiters appear to serve as irritants near the end of an attack wave in order to speed up the battle. They will track you closely. Kill the Baiters as soon as they appear. They're fairly large targets. If too many Baiters appear, you'll probably have to use Hyperspace. They disappear with the destruction of all the Landers.

Bombers
250 points. Bombers are fairly passive. They travel in groups of one to three, leaving Mine Fields behind them. You cannot shoot these Mines. You must avoid them. Try to kill the Bombers before they leave Mines.

Pods
1000 points. Pods are some of your worst enemies. They also yield high points. On contact with one of your lasers, five to seven swirling Swarmers that will attack you are released. The Pods appear at predictable times throughout the battle. A new notice below the Scanner will inform you of the moment when three or more Pods will occupy the same location in space, yielding the optimal opportunity to hit them all at once with a Smart Bomb.

Swarmers
150 points. Swarmers are released from Mother Ships after the Mother Ship has been destroyed. These are no fun. They track you closely. Some people use a Smart Bomb the instant a Mother Ship has been killed. Others skillfully and cautiously kill the Swarmers one by one.

Yllabian Space Guppies
200 points. Space Guppies can appear alone, but they usually travel in packs. They appear to "swim" through the sky, moving back and forth, but generally trying to home in on your position. They will also fire at you occasionally. The name Yllabian comes from the name of one of William's competitors, Bally, spelled backwards.

Firebomber
250 points. Firebombers seem to move randomly through the air with no concern for your ship. However, they will avoid being the same height above the Earth as you, making them difficult to fire directly upon. They are slow moving, but their randomness makes them unpredictable. Approach with caution and destroy whenever possible. Firebombers occasionally shoot Fireballs at your ship, which can be destroyed for 100 points.

Dynamos
200 points. Dynamos move randomly and fly about even slower than Firebombers. Alone, they do not represent a significant threat. However, if left alive for too long, they fire Space Hums, tiny heat seeking projectiles that seek out your ship. Space Hums are difficult to hit, but they are worth 100 points if you destroy one.

Phred, Big Red, & Munchie
200 points, 200 points, 50 points. This group of floating "mouths" appear on particular waves. They have similar behavior to Baiters, appearing when you are taking too long to clear a stage, but they cannot fire. If too many appear, your best best will be to fly away and put as much distance between you and them, before turning around and firing.