Subnautica and Subnautica: Below Zero feature five different Game Modes with one being exclusive to Below Zero. The player can select a Game Mode when starting a new save file; a save file's Game Mode cannot be changed after creation unless the player uses console commands. Each game mode imposes different restrictions (or lack thereof) on gameplay.
Survival Mode[]
To stay alive, the player must manage their Health, Oxygen, and Food & Water levels. A First Aid Kit can be used to restore health, Oxygen can be restored at the surface or by other sources, and food and water come from consumable items.
Health can be lost from hostile Fauna, Fire, Radiation or other Environmental Hazards, or running out of the other resources.
If the player runs out of either food or water, they will gradually lose health. If the player runs out of health or oxygen, they die and lose some of the items in their inventory. The Player can return to where they died to attempt to reclaim their lost items. The player can "secure" their inventory by entering Lifepod 5, a Seabase, or a Cyclops or Seatruck; if the player dies with a secured inventory, they will keep all the items from the last time their inventory was secured along with 1 additional random item that was added to their inventory after being secured, and will respawn in the last place they secured their inventory.
Freedom Mode[]
Similar to Survival Mode, but the player does not need to maintain their food or water levels. The Sustenance section of the Fabricator is not available.
Hardcore Mode[]
Close to Survival Mode, but restricts the player to a single life only; if they die, the game ends, forcing them to start over from the beginning. In addition, the PDA does not warn the player when their Oxygen is low, and you cannot save the game anytime like in the other modes; the only option is to Save & Quit.
Creative Mode[]
Creative is a sandbox mode for players who want to freely explore and build. The player cannot die and does not have to worry about health, oxygen, hunger, or thirst. Materials and Blueprints are not required for crafting, and Vehicles and Seabases do not require Energy to operate and cannot be damaged. In Subnautica, the player can make story progress in this mode, despite the description saying otherwise.
Custom Mode[]
Custom Mode is another sandbox mode that is, as of now, exclusive to Subnautica: Below Zero. Selecting this Game Mode brings up a menu that allows the player to configure the game to how they want to play. Almost all of the aspects of the game can be modified here. The player can also convert their save to Custom Mode at any point from the options menu. NOTE: The player cannot earn Achievements in this game mode.
Bugs[]
- While playing creative mode, the player may die if they are inside a Cyclops when it explodes.
- Dying may cause the player's progress of collecting Prawn Suit fragments to reset. This means the player will need to scan more than 4 Prawn Suit fragments to unlock it.