Here’s an overview of the game, via XSEED:
Set in the ever-evolving Touhou Project universe, Touhou: Scarlet Curiosity trades in the series’ top-down “bullet hell” roots for an action RPG approach, drawing inspiration from series such as Ys while still retaining a distinctly indie feel. In a standalone story that draws upon the series’ 20 years of lore to characterize its two playable protagonists, players take on the role of the titular vampire Remilia Scarlet or her devoted maid, Sakuya Izayoi, as they explore a wide variety of environments and battle aggressive creatures. Fast-paced combat and the series’ trademark complex patterns and waves of projectiles will keep players on their toes as they fight to retake Scarlet’s manor!
Immortality can be boring. At 500 years old, the so-called “Scarlet Devil,” Remilia Scarlet, is desperately searching for something new to end the monotony. After stumbling upon a newspaper article about a powerful and mysterious monster terrorizing the countryside, she rushes out to see if this could finally be the excitement for which she yearns. Unfortunately, not only is she unsuccessful in her search for the monster, but she returns to find her manor in ruins. It would seem the monster has come to her! With a renewed sense of determination (and a much-needed respite from her boredom), she vows to take revenge on this fiend and make it pay!