Uridium

Uridium (released on the NES as The Last Starfighter) is a science fiction side-scrolling shoot 'em up originally designed by Andrew Braybrook for the Commodore 64, and later ported to other 8-bit machines. It consists of fifteen levels, each named after a metal element, with the last level being called Uridium (a fictional metallic element, not to be confused with the real metallic element iridium). The manual quotes Robert Orchard, who invented the name as saying "I really thought it existed".

The solar system is under attack! Enemy Super-Dreadnoughts have been placed in orbit around each of the fifteen planets in this galactic sector. They are draining mineral resources from the planetary cores for use in their interstellar power units. Each Super-Dreadnought seeks out a different metal for its metal converter.
Your Manta class Space Fighter will be transported to each planet in turn and it is your task to destroy each Dreadnought. First you must attack the defensive screen of enemy fighters, then you must neutralise the majority of surface defences before you land on the Super-Dreadnought's master runway. Once on board you must pull as many fuel rods as possible from the metal converters before you take off for a final strafing run as the Dreadnought vaporises into the ether.