Epic Games is offering Subnautica for Windows and Mac as a FREE (regularly $24.99) download for a limited time. Deal expires December 27, 2018.

Created by Unknown Worlds Entertainment. Descend into the depths of an alien underwater world filled with wonder and peril. Craft equipment, pilot submarines, and out-smart wildlife to explore lush coral reefs, volcanoes, cave systems, and more – all while trying to survive.