Your ship is able to collect many small power-ups to build their weapon's power. Players could then unleash a large beam attack or a screen-filling energy burst that would drain their power level back to zero.
The year is 2042: Earth gets invaded by aliens intending to plunder Earth for inorganic materials. Both the aliens and the star they came from became known as "Nemesis". Earth's troops put up a fight, but were outmatched by the alien's powerful beam weapons. However, Earth's scientists managed to obtain the aliens' weaponry for Project Metal Black, which focused on developing at least 20000 human space craft with the same beam weaponry. The space craft was known as the CF-345 Black Fly.
Ten years after the invasion, Earth unconditionally surrendered to the aliens and promised to keep all of Earth's remaining forces from attacking. This applied to Project Metal Black as well and sealed the Black Fly space craft from the people. The aliens ended up devastating Earth anyway via draining its natural resources, and the dying planet's capacity to sustain its population was rapidly diminishing... it was only a matter of time until someone discovered legacies of Project Metal Black and struck back.
This game provides examples of:
- After the End: The aliens have managed to conquer Earth and diminished Earth's resources. Stage 1 (a wrecked city) shows the extent of the damage done.
- Alien Invasion: And the aliens actually win and succeed. The story takes place after they manage to ravage most of Earth.
- Amazing Technicolor Battlefield: The final boss Omega Zone definitely counts.
- Attack Its Weak Point: Most of the bosses have a single weak spot which you have to hit in order to damage them.
- Beam-O-War: You Smart Bomb fires out a giant beam laser when the button is held down. It is able to counter enemy shots, as well as the Wave-Motion Gun that the bosses use.
- Big Creepy-Crawlies: Daio & Gishiin, a mechanical dung beetle rolling a ball of scrap metal.
- Bittersweet Ending: The bad ending. The Hero Dies, but inspires the rest of the military to resume fighting. 20000 Black Fly ships set out for battle.
- Charged Attack: Collect-type. You collect particles of "Newalone" energy to power up your beam cannons (which act as a Smart Bomb or a Wave-Motion Gun).
- Collision Damage: Against almost all enemies. However, averted by the Final Boss (only his core can kill you on contact, his body and tail are harmless).
- Deadly Walls: Yep, hugging a wall will kill you in this game, like most traditional shoot-em-ups.
- Eldritch Abomination: The Nemesis, as they are biomechanical monstrosities that resembles aquatic animals yet fully capable on traveling and fighting at zero gravity and the bosses explode in cascade of trippy colors after defeated. Especially the second boss, which are able to disguise itself as a moon, and the final boss, which can warp reality itself.
- Flying Seafood Special: Many of the bosses and enemies are based off aquatic animals as a homage to Darius series.
- Gainax Ending: The game ends after a spectacularly trippy fight against what appears to be the Nemesis leader itself. After defeating it, it is shown that Earth inexplicably cut in half, cut to the image of the pilot of your spaceship in a fetal position, and a broken English narration that imply the whole story is All Just a Dream... Averted if you lose at the boss fight, however; see Bittersweet Ending above.
- Giant Enemy Crab: The Mini-Boss of stage 1 is a giant hermit crab with an aircraft carrier as its shell.
- Grand Theft Prototype: Decades after aliens destroyed Earth and the world's governments unconditionally surrendered, you steal an experimental space fighter and blast your way through re-animated carcasses of Earth's military forces that didn't survive the alien invasion while attempting to escape into space to fight the enemy hordes. The game has multiple endings depending on if you win or game over in a certain stage, and one ending involves the governments being motivated by your death into bringing another 20,000 experimental fighters into action.
- Kaizo Trap: There's one section in the Stage 4 where the wall below will quickly rise and block your way, costing you a life if you haven't moved all to the right.
- Mind Screw: The "good" ending. If you can make any sense out of this, you're good. (more pictures here)
- One-Man Army: Justified, as the other humanity has surrendered to the alien forces and you fly one of the "Black Fly" spaceship in secret.
- Power-Up: Only one kind, which look like three coloured particles stuck together. These things power up your regular weapon as well as charging up your Smart Bomb.
- Segmented Serpent: Feeder, a giant mechanical [[Rat-tail fish]]. Attack its head in order to damage it.
- Smart Bomb: Tapping and releasing your secondary attack button will allow you to shock the whole screen in energy.
- Soundtrack Dissonance: "Born To Be Free", Stage 1 music. An upbeat, hopeful tune played over the landscape of an Earth utterly devastated by aliens draining the planet's resources to near-exhaustion and infested with not only re-animated remains of Earth's military forces that fell during the invasion but also organisms of the said alien occupiers.
- Spiritual Successor: To Gun Frontier, technically. This game is referred to as Project Gun Frontier 2 in the credits, and both were indeed developed by the same team, as seen in their unique palette style and the music used in the attract demo's opening. However, Metal Black plays almost nothing like Gun Frontier, instead employing the "beam battle" weaponry that would reappear in the Darius series.
- That's No Moon!: You see a moon in stage 2, shortly after leaving Earth. Turns out that you see the real moon after that, and the first "moon" is the egg of Feeder, the second boss.
- Translation Train Wreck: Strangely, all of the texts are 100% in English even in the Japanese version, and they're spectacularly awful, even by Taito's Engrish standard. For example, your ship's sole power-ups, "Newalones", are actually supposed to be Neurons.
- Wave-Motion Gun: Your Newalone energy cannon, reverse-engineered from the aliens' weaponry. It is able to destroy enemy shots too.