The goal of the game is to save the five cities on your planet from being hit by the red plasmabombs of the aliens. You can scroll the screen to the left and the right side by moving the mouse pointer to the left or the right border of the applet. You can kill a alien Ufo by clicking on it with your mouse pointer. If you hit a blue ufo it will be destroyed immediatly, if you hit a red one, you have to hit it five times before it will explode. The ufos try to hit your cities with their bombs. If a city is hit by such a bomb it will be destroyed but you can save your city with a shield when you click on the city before the bomb hits the ground (this city will be saved against all bombs for a few seconds). Bad news, you have only two shields per game ;-) . Sometimes you can hear a bonus sound effekt. Then you have to watch out for a green ufo. If you hit this green ufo you will get a new city or a new shield.
Your laser cannon will have to be reloaded after 10 shots so press the "return/enter" - key to reload it with 10 new shots. When all your cities are destroyed the game is over. Have fun!