As a Space Invaders clone, your task in this game is to defend the Earth against endless waves of incoming aliens. The more you kill, the faster they go; if they complete their winding descent down the screen, your mission is over. Each row in the orderly squadrons is populated by a distinct breed of vaguely-insectoid intruder, and their point values vary accordingly - you get less for zapping the cannon-fodder at the bottom, more for the higher-ups. (mobygames.com)