“THE EARTH DIED, AND IT WAS ABOUT TO ENTER UPON SILENCE TIMES…”
Metal Black is a horizontal STG/“shmup” originally released in 1991 by Taito. It started development as an entry in the Darius series, but became a sequel to 1990's Gun Frontier, although the games share little in common. (There are some aquatic enemies that reference its Darius origins.) It was an early attempt at marrying visual storytelling and serious thematic elements to the STG genre, and is quite progressive even by modern standards. Gameplay was also streamlined from the Darius series: the only powerup is the ubiquitous Newalone, and your one secondary attack is a long-lasting beam that can be used in dramatic “beam duels” with bosses.
The plot, told in fast-scrolling Engrish during the attract mode, is remarkably well-told and developed for the era. It involves an alien invasion from the “sky area of Nemesis,” coupled with an asteroid attack from the gravity of a new star they created. Earth's military develops the Blackfly fighter to combat this, which uses the same Newalone energy source as the aliens' beams. However, Earth foolishly makes a “compromise called peace” with the aliens, freezing the Blackfly project. The aliens obviously don't uphold the truce, since all civilization is destroyed, turning cities into deserts. A lone Blackfly pilot then defies the freeze, setting out against the enemy.
The final boss is especially notable: a duel with an ephemeral dolphin-being, set against a slideshow of human history and its tragedies, culminating in the destruction of Earth. There are multiple endings depending on if you win or not, possibly a first for the genre (anyone know for sure?).