Attention all Earthlings! Relentless alien hordes have been identified near you. Be aware the classic arcade update has proven to be even more dangerously addictive than ever before. Battle squadron after squadron of alien forces as they pulse down through the menacing sky. You must save the galaxy in 100 levels of lightning-fast arcade action. Test your rapid-fire skills against 13 deadly enemy species and 10 huge bosses as you defend the galaxy from constant invasion.