Hostile aliens are pursuing the human race across the galaxy to deliver a devastating final blow. To save mankind, you must navigate one of 12 ships across a scrolling 3D combat zone and unleash its guns upon an unrelenting stream of aggressors. Although you will face more than 50 different enemies and six massive bosses throughout 30 levels of intense action, your arsenal includes 10 upgradeable weapons, 10 powerful missiles and power-ups that tip the odds of survival in your favor.