Destroy all alien invaders before they reach Earth. The aliens march side-to-side and drop lower with each pass. As you destroy them, they move faster. Use the 4 shields for cover — but shields erode from both sides!

• The Mystery Ship appears periodically at the top — shoot it for bonus 50-300 points.
• Only one bullet on screen at a time — aim well!
• Each new wave the aliens start lower and faster.
• The last alien moves extremely fast — be ready!