"Crystal Soul" - original idea for 2D adventure, fantasy game (BA thesis)

The main character is Richard Astley. He's a biologist and runs a family business that revolves around discovering, studying and protecting unknown specises of flora and fauna.
When the world faces attacks of unknown beings, called Oreads, Richard is trying to find a way to stop them. For this purpose he descends into their hidden, undergroung world. During his journey he's stating to discover links between him, his family and Oreads. It turns out he's a descendant of one of the Oreads, who many centuries ago separated from its kind to live among humans. If Oread ever wanted to come back it could use a magical artifact to connect to their collective awarness again. It never happened so the artifact stayed in Astley's family for many years.
Richard also learns that once highly developed civilization of Oreads now is in decline. Many Oreads kept self-awarness and stayed in caves protecting what remained from their home. Many others, however, became wild and started attacking people as their crystal soul corruped and darkened.
Are Oreads sentenced to extinction or is there a way to save what has been lost?