Uridium is a science fiction side-scrolling shoot 'em up for the Commodore 64 (and 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).
In practice, each level takes place at a fixed altitude just above the surface of the Dreadnoughts. The screen scrolls horizontally in both directions as the Manta flies over the Dreadnoughts. Each Dreadnought has a different configuration of walls and other high structures which must be negotiated in order to reach the landing zone. This task is hampered by squadrons of enemy fighters that attack the Manta in waves. Lastly, flashing ports on the Dreadnought's surface release homing mines that cannot be destroyed. It takes a skillful Manta pilot to outfly the mines until they self-detonate.
Source: Wikipedia, "Uridium", available under the CC-BY-SA License.