A huge meteor is about to hit Earth and on closer inspection you will notice that an alien armada is just behind it. Humanity rests on your shoulders as you fly into space and destroy every last tidbit of rock before it impacts the Earth and creates colossal damage. Your ship is built with both a primary weapon and secondary weapons. Primary weapons are unlimited so it's best to use them every chance you get whilst secondary weapons are fairly limited so use them only in crisis situations. As you go along, you will have better weapons ranging from Straight Missiles, Homing Missiles and even Parasitron. Blast those alien freaks in Star Defender 4.