Cuboids for Mac OS

The year is 2198. As you return from a routine mission in the Andavarian region, you find EARTH surrounded by hundreds of strange, alien spacecraft that you can only describe as... cuboids. Earth`s forcefield is preventing the aliens from doing any damage to the planet, but it is slowly losing power each time it is hit by the weapons aboard the alien ships. You must now take on the task of ridding the solar system of these enemy craft. Your ship is equipped with an implosion Cannon that will destroy the enemy ships. You must time your shots well, however, because each time one of your shots misses the cuboids, it goes past them and hits Earth, further weakening its forcefield. Good luck, for if you fail, it will surely mean the end of mankind.