A player, who operates the main Strategic defence station, must protect the Earth from comets, meteorites and fireballs. The space objects have different paths of motion (direct, cyclic or free fall). A player must make a shot using a plasma ball, take into account speed and path of motion of the object. In the game there are real show-places of 10 European countries and USA. If a player strikes, he gets the scores. If a player shoots down two objects at one stroke, he gets a bonus - annihilator. Using annihilator a player can destroy all the objects but without any extra scores. During destruction of buildings by space objects a player loses scores. Managing the game is held by the mouse. You can get the next level only having a positive number of scores. Making a shot (left mouse button), launching of an annihilator (double click), an explosion of the last plasma ball in the place it had time to fly (one click on the base). All the game information is shown on the indicator panel : a temperature of station locator, an opportunity to shoot not more than 3 times running, a type of danger of the space objects, a number of scores, quantity of shots and geographical area. On the station (locator) there is an indicator light of complexity and danger of the current game level.