The object is to destroy the oncoming enemy planes, so that they do not reach your base.
The planes do not fire, instead they try to collide with you.  After each squadron of planes a bomber tries to pass you, if he does you lose a plane.  It takes multiple hits to disable the bomber.
Use the Fire button to fire bullets, and use the directional keys to move left, right, up and down.

Scoring:
10 points for each plane shot.
100 points for each bomber shot. 
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