Destroy the aliens with your laser base. Use 1 to move left, 2 to move right and 0 to fire.
Your game is over wheneither your base has been hit thrice by the aliens, or the aliens reach the bottom of the screen.
Extra points are awarded for hitting the flying saucer. Affter you hit thirty aliens, they will come down two levels just to annoy you.
1 . . Left
2 . . Right
0 . . Fire
Please Note that this game will not work correctly with some emulators, including EightyOne. This due to the way the emulators scan the key presses in the emulation code. We hope this will be fixed soon.