Subnautica: Below Zero is a survival adventure game set in an open world environment and played from a first-person perspective. Like its predecessor, the player's goal is to explore the environments and survive in an alien environment while also completing objectives to advance the game's plot. Players collect resources, construct tools, build bases and submersibles, and can interact with the planet's wildlife.[1]
To survive and complete objectives, player must collect raw materials from the environment and craft equipment, vehicles, shelters, and food. Each of these has its own recipe, and some ingredients can only be found in the far-flung and deeper corners of the game world. Habitat structures provide shelter, storage for equipment and collected materials, and crafting stations. Inside a habitat, the player can also craft living amenities such as beds or coffee tables, although these are purely cosmetic since the game does not track fatigue.
Each piece of equipment that can be crafted has its own recipe and the player begins the game knowing only a handful of recipes. The player learns new recipes by scanning scraps of technology or recovering databoxes, which are strewn across the game world. Alongside raw materials, finding new crafting recipes is a major reason to explore.
Generally, the game requires the player to visit ever-deeper sections of the game in order to find exotic materials, technology to scan, and complete objectives. In fact, the final objective of the game is located at the deepest point in the game world. The main issue with accessing deep sections of the water is oxygen capacity. At the start of the game, the player character can only hold her breath for 45 seconds and even less at depths below 100 m. The player must craft equipment that will allow them to stay underwater for longer, such as high-capacity oxygen tanks and vehicles. Habitats and vehicles provide oxygen while powered, but vehicles need to be upgraded in order to withstand the water pressure at greater depths.
The game primarily takes place underwater, but, unlike its predecessor, there are also expansive land-based areas to explore. There are explorable structures to find both above ground and underwater, which serve as key locations for the story, as well as sources of new blueprints used in crafting. In addition to the day-night cycle, there are dynamic weather effects, such as wind and fog, which further affect visibility. The game introduces new gadgets like the Headlamp, Mineral Detector, and Booster Tank.[2]
Alongside returning mechanics such as oxygen, hunger, and thirst, players now have a body heat gauge which comes into play when walking on land. It functions much like the oxygen gauge does underwater. The player will gradually lose body heat and eventually die of hypothermia, unless they can replenish their body heat by jumping into water, consuming certain items or standing next to a heat source.