The Waters Above: Prelude

A giant dome called the Vault of Heaven covers the earth, separating it from the vast ocean of the heavens. In this world, sea nymphs care for the stars in the sky, dedicating their lives to it. However, magic is fading, the stars are dying, and no one knows why. No one even speaks of it, carrying on like they have for tens of thousands of years, as if nothing has changed. In these circumstances, three sea nymphs and the living embodiment of a star struggle to find meaning in their lives and their fading world.

[From itch.io]

The Waters Above: Prelude was a prequel story to a planned game called 'Starkeeper: The Waters Above', but the latter has since been canceled.