Metal Black was a shmup for the arcades; it has later been ported to Sega Saturn and, as part of Taito Legends 2, to Windows, PlayStation 2, and Xbox. The game may have at one point been a project for Darius III, but due to the dark nature of the plot Taito redubbed it Project Gun Frontier 2, as a sequel to the Western-themed shmup Gun Frontier (A.K.A. Gun & Frontier) 
The year is 2042: A companion star of the planet Jupiter appears a few Astronomical Units away from the planet and not long before its discovery propels the asteroids along Jupiter's orbit which sends a wave of meteorites towards the Earth. As the Earthlings struggled to survive, extraterrestrial cybernetic invaders from beyond the distant star used the meteorites as cover for invading Earth with little resistance, intending to plunder Earth for inorganic materials needed to sustain their forms. Both the aliens and the star they came from were quickly dubbed Nemesis.
What resistance the aliens did face from Earth's combined international defense forces were quickly obliterated by the alien's powerful beam weapons. Earth's scientists studied the molecules that powered the alien's weaponry which started to litter the Earth and called the molecule 'Newalone.' With Newalone in their hands, scientists quickly began Project Metal Black, which focused on developing at least twenty-thousand human space craft capable of wielding the same beam-weaponry as the aliens. The space craft was known as the CF-345 Black Fly, named by its method of Newalone energy use.
However, ten years after the invasion, Earth's remaining diplomats passed a treaty on to the aliens under a peaceful surrender, which promised to keep all of Earth's remaining forces from attacking: This applied to Project Metal Black which sealed the Black Fly space craft from the people. The Earth's natural resources were dying and the planet's population was thinning... it was only a matter of time until someone discovered Metal Black and struck back.
Levels and Bosses
Similarities with Darius series
While Metal Black ultimately did not become part of the Darius series; many traces of its roots, and it's subsequent influences on later Darius installments, can be seen throughout the game. These include:
- The shark jaws on the logo are a reference to the marine life forms featured on the Darius series.
- The conflict between Earth and Nemesis closely parallels that of Darius and Belser.
- Like in the Darius series; the enemies in Metal Black consist, for the most part, of cybernetic animals.
- Thought they visually are rather different, the shape and size of Metal Black final boss Omega Zone is close to that of recurring Darius final boss Great Thing.
- The beam battles used in Metal Black are later used in the same manner in G-Darius.
- The explosion animations shown when defeating a boss is similar to those in Darius Gaiden.
- The origin of the Black Fly and the Silver Hawks are close in that the both are one-pilot, air-plane-like ships created using enemy technology and energy-sources, and later are used by the protagonists to defeat that enemy.
- The Black Fly and Silver Hawk are both named after a color and an animal, in that order.
- Metal Black has mid-bosses/Captains similar to those first used in Darius II.
- In both Metal Black and the Darius series; sirens are heard as harbingers for every boss-battle.
- The in game sprite for the Newalone is almost identical to that of the Tricolor Power-Up in G-Darius.
- The mid-boss on the first stage is very similar to Yamato from Darius II.
- The Ocean Sunfish on stage 2 and stage 4 and the ranking screen are similar to Heat Arrow from Super Darius II and precursors of Odious Trident from Darius Gaiden.
- Feeder is the successor of Driosawm from Darius II.
- Amazo is the precursor of Titanic Lance from Darius Gaiden.
Intended plot as Darius III
When development began on Metal Black as Darius III, the plot would continue where Darius II ended, where Proco Jr. and Tiat Young would return from the Solar System, only to find Darius horribly ravaged by Belser's Army. Taito, however, ultimately decided that this was too bleak (and dark) as a scenario for the Darius series, assigning it as the sequel of Gun Frontier, however Metal Black's events happens 78 years before the events of Gun Frontier.