Sunken Fossil World

Sunken Fossil World (東方剛欲異聞　～ 水没した沈愁地獄) is a side-scrolling action platformer and the seventeen-point-five official installment of the series.

Story
One day, foul-smelling, oozy black water gushes out onto the surface. It raises many questions, piques interest, or causes worry. This water eventually starts replacing the once clear natural springs and streams of Gensoukyou. The protagonists head to the Underworld once more to fix this incident.

Gameplay
The game features a total of eight playable characters, though two of them function as a duo. Only two characters are unlocked by default: Reimu and Marisa.