Planet 4546B, an unexplored world on the edge of explored space.

The site of a desperate attempt by the Precursor civilization to find a cure for the deadly Khaara Bacterium. A thriving ecosystem only disturbed by the presence of the plague the Precursors left behind.

However, a lone unicorn named Twilight Sparkle has been thrown into this vicious world of ocean, having lost the battle against a time-manipulating foe. She tries her best to survive on one of the few spots of dry land available in the endless oceans.

But when the Aurora is shot down, and Twilight discovers a deadly infection spreading through her and the wildlife, she discovers she has to dive deeper, delve into the last holdout of the Precursor Race.

The last holdout of a nation that seems all too familiar...

Crossover with Subnautica. Spoilers ahead.