There are five types missiles that you can purchase or get as bonuses:
MISSILE(COST) - DESCRIPTION Straight ($120) - Fires two missiles in a straight trajectory. You must be lined up with your target. Smart ($400) - Seeks out the enemy target on its own. Medusa ($750) - Larger missile that causes more damage. Swarm ($1,200) - Unleashes a swarm of short-range missiles that do heavy damage. Nuke ($2,400) - Best missle.
Bosses dash around and fire the following three different weapons at you. The key to destroying the boss is to learn the timing of each weapon being fired at you. Dodge as much fire as possible while laying down some thick weapon fire while blasting it with your missiles:
ATTACK - DESCRIPTION Straight lasers - Two solid streams of laser fire that last for a few seconds. They are spaced very close together. Do not position yourself between them. Scatter shot - A group of small green plasma balls… There is almost no way to dodge them, but their damage is less than the straight lasers. Missiles - A slew of missiles that fly in arrow formation. Chances are that you will be able to dodge most of them with some skill.
-When you need to "repair all" after ay battle, press ESC]and start the game over before starting the next battle. This will automatically "repair all" on its own. It will not show this until you are on the actual battlefield. Another way is to click the "Reset" button and it will repair.
-A free "repair all" happens at the start of each of the five worlds.
Sometimes you can collect a bonus after destroying an enemy ship. Bonuses are normally extra money or missiles, but you can also get special shields that make you invincible for a limited time or repair bonuses to your shields. You must collect the bonus without getting hit by enemy fire. The best way to wait until it gets slightly closer then zoom in, take it, and zoom back out.
Avoid using overly powerful weapons as it changes what shows up when you blow up the drones. Some of those upgrades will not show if you start blasting with nukes or over blasting with weapons. It helps to be conservative with your weapons.
There are only a couple times to use nukes, such as during the second battle of world 4 where there are two rocks that go by after the first larger ship that spits out the little people in front. Only the nukes will destroy those rocks (asteroids).