Get ready for wave after wave of lightning fast kill-or-be-killed action as merciless alien attackers dive, swoop, and drop bombs on your defense ship. You are responsible for overseeing a uranium refueling operation, and the aliens are hell bent on stealing as many canisters as they can get their claws on.
Move your ship back and forth across the bottom of the screen, shooting straight upwards at the diving aliens. The uranium canisters are arrayed across the bottom of the screen and are slowly being transported to the refueling point at the bottom left corner of the screen.
If an alien gets hold of a canister, it will lift it straight up. Shoot the alien before it gets to the top of the screen to reclaim the canister, but don't get squashed when it falls back to the planet surface!
Switch up your gameplay with a combat round - shoot the alien ship moving across the top of the screen when the word Combat is displayed and you'll find yourself in a one-on-one duel against the alien ship.
The wave ends after all canisters have been removed from the screen and refueling has been completed. Save all fifteen canisters for a big bonus score.