Subnautica is an open-world survival game in which a player takes on the role of a terraformer engineer, having escaped the starship Aurora just before it mysteriously crashes onto an alien planet. The planet is mostly covered by water and the player must adapt to this new alien environment, gathering food, building a habitat and discovering the secrets to why the ship crashed.The player begins in the still functional escape pod, equipped with a material synthesizer and a distress beacon. As is the style for building games progress is made by venturing underwater, finding useful minerals, and returning with them to the synthesizer to make new tools. Once the Habitat Builder is created the player can start building a more permanent underwater home, with every room and amenity laid out as the player wishes. The next step is to build underwater vehicles to expand the range of their operations, up to and including a submarine that the player can walk inside of.While the player starts with a small number of schematics most buildable items and equipment upgrades are learned by scanning an intact or several broken examples of items found in the Aurora’s wreckage. The player will find new regions with their own flora and fauna as they journey farther from the starting area, and they will run into ever more dangerous and weird predators the deeper they travel. The distress beacon will occasionally pick up other messages, directing the player to find the fates of the other escape pods.At present the game has four game modes: Hardcore (Hunger & Thirst, Power drain, and Permadeath), Survival (Hunger & Thirst, Power drain), Peaceful (Power drain) and Creative (No limits).