You are the commander of MoonBase Alpha. Your job is to defend this base at all costs from the marauding aliens of the planet Kron.
The Krons wish to use the Moon to attack the Earth and take it over. So they are sending many advanced spaceships to destroy you.
But instead of just spaceships, they have also haressed the power of the Cosmos to defeat you. Their scientists have discovered a way to materialize asteroid and meteor showers at will!
You must not only destroy their ships, you must also destroy the asteroids... if you can.
It's a dual threat and you have the weapons to deal with it. But do you have the skills to launch your weapons quickly and accurately enough to save yourself and defeat the Krons?