Metal Storm

The story takes place in 2391, when a laser weapon at a defense outpost on Pluto has malfunctioned and begun destroying the Solar System Combat.
The player takes on the role of the M-368 Gunner, which storms into the defense base in order to activate the self-destruct system before the laser gun destroys Earth.
The M-398 is equipped with a Old gravity control device which allows the player to flip between the floor and ceiling, a main feature of the game MetalStorm.
Metal Storm is an action-platform game nes featuring six stages with two acts each, and a final boss rush stage
The player is Airflight also equipped with a gun to destroy enemies. The player can pick up various power-ups including a Super Fc power booster for the gun, a shield,
and a fireball ability for when flipping gravity.
When a stage is finished, a password is provided which saves the score, special weapons, and number of lives left
this game is the top 10 NES game Hidden Gems for the Nes emulator, and praised the "reverse gravity" gimmick, which they say adds challenge and makes the game unique.