Dezatopia

Strange and unusual creatures inhabited Earth’s underground, beyond the reach of sunlight and human eyes. This was until Momoko, a fashion-obsessed high school girl, accidentally discovered them. Together, they plotted to combine the civilizations above and below the surface to create a new world: Dezatopia. Akane and Aoba, two of Momoko’s schoolmates, were hired to help start construction of the towering subterranean bridge. However, on the verge of completion, they discovered the extent of her plans and decided to sabotage the operation. Their only hope of repelling the waves of beasts loyal to their human queen is their work ship, the Speleological Fighter Pink Aurora.

A horizontal shooter in which the player controls a four-way shooting ship in a world dynamically changing its difficulty to match the player's skill level.