Gunrunner

Planet Zero is in an indefinite ice-age, and its people can only survive via a network of pipes supplying heated nuclear power. The inhabitants of planet Destrovia have come to steal as much of the plutonium being used as possible, and it's your job to stop them.

Essentially you do this by flying from left to right and shooting those alien waves. You must jump over many boxes and other barriers, but can use these to gain a safe place. Bonus items on offer include 3-way fire, a 'poison' smart bomb, a shield and a jet-pack. Each of these has a limited length of time in use, but if you are carrying one, you lose the item rather than a life.