Blaster Master

One of the games created for the Nintendo Entertainment System, this video game combined the side-scrolling antics of a vehicle with the overhead sections of gameplay of the pilot as he entered dangerous areas of the underground land he had fallen into.

The story itself seems to detail the hero, Jason, following his pet frog as it hops out to a box marked radioactive. The frog, apparently drinking from the box, then grows to a large size. The ground the box was settled on collapses, and the frog falls into the hole while Jason follows it.

That is when the boy discovers the vehicle which you play most of the game in.

Story
The plot of Metafight is centered around Kane Gardner, pilot of the battle tank, "Metal Attacker", who lands on the planet Sophia the 3rd to lead the attack against the invading emperor Goez.

In Blaster Master (the localized version of Metafight), the player controls Jason Frudnick, a teenage boy who fell into a humongous underground cavern after chasing his pet frog, Fred, who has become enlarged, due to exposure to radiation. There, he discovers an all-terrain battle tank. This vehicle is designated SOPHIA (sometimes also referred to as Sofia), which stands for "Subatomic Omni-directional Probative Hyper-responsive Indomitable Abdicator (3rd Design) Nora MA-01". As he explores the underground world, he must find the underboss of each of the eight levels and destroy them. After he destroys each underboss, he is given an upgrade with which to enhance SOPHIA the 3rd. When he reaches the end, he discovers that the underbosses were controlled by the Plutonium Boss, a creature which was planning to invade the world above.

The story of Blaster Master is sometimes criticized for being confusing and incomplete. For example, Fred's mutation is brought about after he hops onto a radioactive chest inexplicably placed in Jason's front yard and no explanation is given for either the radioactive chest, or SOPHIA's convenient location. The plot of the Blaster Master Worlds of Power book, which is slightly different from that of the manual, goes into more detail and explains many of these quirks. However, the Worlds of Power book was originally not canon to the storyline of Blaster Master. See the Novel section below for more information.