History Videogame / Subnautica

** In real life, vehicle crush depth can't be improved by simply improving the technologies involved; that would require (at minimum) a redesign and strengthening of the hull, and same goes for installing torpedo tubes or miniature storage lockers. For the sake of gameplay, all installed expansions simply provide their benefits.

A sequel titled ''Subnautica: Below Zero'' was released to Steam Early Access on the 30th of January 2019, set in an icy region of 4546B. ''Below Zero'' was later fully released on May 14, 2021. A currently-untitled third installment was confirmed to be in production in April 2022; as of January 2023, no other details have been revealed.

On the way, you will face various {{Primal Fear}}s: swimming through {{Creepy Cave}}s that are dark and twisted enough to get lost in, running AlmostOutOfOxygen and nearly drowning, getting dangerously close to hungry {{Sea Monster}}s, and more. The game leans heavily on SurvivalHorror tropes without quite fully crossing the boundary into the genre. This makes for a tense experience with bouts of both terror and wonder. In short, it is a plot-heavy survival crafting game with [[TheWorldIsJustAwesome added OMG]].

** Creative Mode: no hunger, thirst, oxygen or health meters so the player cannot die outside of specific bugged situations[[note]]f they're caught in a Cyclops explosion (only doable in Creative Mode via console commands), or stands beneath the elevator on the Neptune Escape Rocket[[/note]], vehicles and seabases don't require energy nor can they be damaged, and you don't need materials or blueprints to craft.

** Creative Mode: no hunger, thirst, oxygen or health meters so the player cannot die[[note]]Due to a bug, the player can die if they're caught in a Cyclops explosion (only doable in Creative Mode via console commands), or stands beneath the elevator on the Neptune Escape Rocket[[/note]], vehicles and seabases don't require energy nor can they be damaged, and you don't need materials or blueprints to craft.

** Survival: standard difficulty.
** Freedom: like Survival, but without hunger and thirst.
** Hardcore: like Survival, but with permadeath.
** Creative: no hunger, thirst, oxygen or health meters, and you start with most blueprints and raw materials available.

The game is set on an alien ocean world, designated Planet 4546B. The player is the [[{{Robinsonade}} sole survivor]] of a crashed capital-class ship named the ''Aurora''. The lifepod with which you escaped the ''Aurora'''s destruction is equipped with a fabricator, which you must use to cook fish, disinfect water, craft tools, and more. You must explore the underwater landscape of Planet 4546B to find resources and blueprints, build seabases and vehicles, and discover just why the ''Aurora'' crashed in the first place, all the while trying to survive the dangers of the deep. All the same, Planet 4546B is filled with strange and beautiful biomes, inhabited by a rich collection of creatures that are no less fascinating than they are dangerous.

* YankTheDogsChain: After everything the survivor goes through, from scavenging for food and water to fending off giant predators, to [[spoiler: curing a disease that has plagued the planet for over a thousand years]], he finally builds a rocket and escapes, only for [[spoiler: Alterra to claim that he owes them one trillion credits for all the resources he scavenged, and they won't grant him permission to land until he pays it. Better hope you can barter off all the information gathered from scanning the items in 4546B, as well as bringing Architect tech back to barter off[[note]]though even that might not work, since Alterra preemptively claimed everything on the planet was their property to begin with[[/note]] and/or that it's actually not as big a deal as it may sound, since we have little-to-no understanding of ''Subnautica'''s economy rates.]]

--->''"I thought it might get claustrophobic, living underwater. [[{{Jerkass}} Father]] feels it is. He'd tell me it was childish, but I stare out the window and sometimes I think how lucky I am to see this world up close. Back on the island, I wouldn't have believed the creatures that live down here. The fish, they ''[[BioluminescenceIsCool glow]]''... there's one that's 90% eyeball... Snakes twice the length of a habitat compartment..."''

* YankTheDogsChain: After everything the survivor goes through, from scavenging for food and water to fending off giant predators, to [[spoiler: curing a disease that has plagued the planet for over a thousand years]], he finally builds a rocket and escapes, only for [[spoiler: Alterra to claim that he owes them one trillion credits for all the resources he scavenged, and they won't grant him permission to land until he pays it. Hope you can barter off all the information gathered from scanning the items in 4546B, as well as bringing Architect tech back to barter off, and even that might not work, since Alterra preemptively claimed everything on the planet was their property, to begin with.]]

** The Cyclops is awesome, but it's also large and unwieldy, which can make it difficult to navigate many of the tight deep sea cave systems it's meant to explore. This isn't helped at all by the multiple Leviathans down there that it can't outrun as it could in open waters, meaning you'll have to be ready to make repairs on the fly while surrounded by scorching temperatures and hostile fauna. Veteran players with intimate knowledge of the cave layouts and entry/exit points may have an easier time, but an upgraded PRAWN suit is much more versatile when it comes to exploring the game world's deepest reaches. It also isn't easy to keep charged, as it can't be docked at a Moonpool and runs on six Power Cells. The thermal charging upgrade can only be built after reaching the deepest depths, and it doesn't do much good on the surface unless you parked your base near a surface vent. However, they do have some use as a mobile base, particularly one to help deploy the PRAWN suit at closer distances if you don't already have a base nearby.

* ItemCrafting: You start this SurvivalSandbox game with nothing. You will need tools, supplies, and vehicles. You have to fabricate them all yourself.

** Growbeds and plant pots allow you to grow flora at your home base without having to risk a trip to the relevant biomes. This is especially useful for underwater flora like gel sacks, which are required component for more complex items.
** Players have devised a trick for farming Stalker Teeth: approach Stalker territory and drop a handful of scrap metal pieces in the outer area. The closest Stalker will soon proceed to swim back and forth between the pieces, mostly ignoring the player while losing teeth regularly.
* JumpJetPack: Built-in feature of the PRAWN Suit. This MiniMecha does not float, so when you pilot it you WalkDontSwim. Jets let you jump off the seafloor and propel yourself upward for a limited time, providing some vertical mobility. An upgrade will improve the jump. It is only designed for relatively low-gravity or high-pressure environments, making it effective underwater but still not very useful on land. In ''Below Zero'', the PRAWN Suit's jets can also propel you forward.
* {{Kaiju}}: The infamous Leviathan-class lifeforms are gigantic, measuring between 55m (Reaper) and 200m ([[spoiler:Sea Emperor]]) in length. It's probably [[ShoutOut not a coincidence]] that some of them bear more than a few similarities to the villainous monsters in ''Film/PacificRim''. Their database entries also lampshade that these monsters are rapidly approaching the [[SquareCubeLaw size limit for sustainable organic lifeforms]]... which is immediately turned on its head when you find the aptly named Gargantuan Fossil, the remains of an ancient super predator that died roughly 3,000,000 years ago before it came to rest in the Lost River Bone Fields. Its skull alone is almost 100 meters long (large enough to swallow the Cyclops whole), its canines measure 10-12m, and the whole creature is estimated to have exceeded 1,200m in length back when it was alive. Kinda makes Reapers, Ghosts and Sea Dragons look cuddly when you realize this thing ate those for breakfast.
* KilledOffForReal: If you somehow manage to actually kill a Leviathan-class creature, it will thankfully stay dead and never respawn.

** The PDA uses the term "Leviathan Class" to describe only the biggest biologically feasible fauna. Note that this is just a size classification, the [[GentleGiant Reefbacks and Sea Treaders]] are considered Leviathan Class.
** On the other hand, if a species includes the word "Leviathan" in their actual name (e.g. Reaper Leviathan, Ghost Leviathan), it's probably best to [[NamesToRunAwayFromReallyFast run and don't look back]].

** In the [[spoiler:Lost River]] biome, players can come across a few multi-million-year-old skeletons. One, in particular, has jaws large enough to fit the Cyclops comfortably inside.
** A "kraken" type creature is a frequent suggestion on forums and the game's subreddit. There were rumors that such a creature inhabited the Void, but this turned out to be just a rumor.

* LoadsAndLoadsOfLoading: Unless you have a fast computer and ''very'' fast hard drive, you will be staring at that initial loading screen for several minutes.[[note]]Even on a mid-range SATA 3 SSD drive the game can take almost a whole minute to load. Having a budget traditional laptop hard drive (whose speed clocks in at 5400rpm) would probably afford you enough time to go raid the refrigerator for a quick snack while the game is loading. While the game was still in development, the loading time will actually increase the more you interacted with the world due to the way the save games worked. Apparently, this was fixed in the final release[[/note]]. Thankfully the game switches to dynamic loading after that and you'll never see a loading screen ever again once you're in the game unless you quit back to the title screen.
* MadeOfIron: Most hostile fauna counts. It's extremely difficult to outright kill anything larger than a cat. Even the PRAWN Suit's giant drill arm will merely chase off attacking predators like Bone Sharks for a short while; you can drill into one for a full minute or more without the beast dying, and that's next to impossible to pull off anyway without glitches because all predators are much faster than the PRAWN. You need to get really creative if you want something dead.
* MagicTool: The Repair Tool is handheld and can be used to repair almost any device in seconds. The Data Bank encourages you to accept a HandWave about how it works.
--> ''Most people don't care why it works, just that it saved their life that one time -- but in case you're curious, it combines scanner and fabricator technologies to determine the proper specifications for the targeted object, and then rearranges the available physical material to match the original specs.''
** BuildingIsWelding: Early designs had a welder that could be used to repair things. This was changed to the repair tool. It still looks and sounds like a welding torch and produces a spark at the end when activated.

* MeleeATrois: Different species of hostile creatures tend to dislike each other just as much as the player, and will often fight if they happen to be in the same vicinity. In particular, many creatures will automatically attack any warpers that happen to enter their territory.

* MorePredatorsThanPrey: The dev team works hard to avert this one: sure, there are some big, scary fish in the sea, but there are also lots of little, less scary fish that the bigger ones will prey upon instead of you.
* NatureIsNotNice: Most of the predators don't deliberately seek ''you'' out; you just happen to be snack-sized and in the vicinity. They'll just as happily eat small fish. Likewise, the greatest threat in survival mode isn't necessarily the wildlife itself; it's running out of food and water,[[note]]at least until you get a habitat with a fish tank and farm areas built,[[/note]] or running out of oxygen while looking for resources.
* NoBiochemicalBarriers: You're on an alien planet, but it just so happens to have a nitrogen-oxygen atmosphere and liquid water. Most of the sea life is edible, and those that aren't are specifically stated to be poisonous in order to avoid being eaten by larger species, rather than just being incompatible with a human digestive system. Of course, this is [[AcceptableBreaksFromReality somewhat necessary]] for the game to be enjoyable to play,[[note]]as it's rather hard to survive when there's nothing to eat or the very air burns your face off,[[/note]] though it ''would'' be nice to imagine you at least give the Reapers indigestion after they eat you for the hundredth time.

** Scannable fragments that unlock new blueprints tend to be a bit less obvious, but they do stick out from among the worthless rubble once you know what to look out for, and they also trigger a small scanner icon in the lower right corner of the screen when you enter their rough vicinity to alert you to their presence (helpful in wrecks because the fragments often blend in very well with the walls and floors).
* NotTheIntendedUse: The Picture Frame is meant for pictures taken in-game. However, since those pictures are stored in a folder, it is possible to take any image that you want, place it in the folder, and then have the game treat it as another in-game picture. This can be used for an extra level of base customization, but the most popular use is to upload a user-made map because the game has no mapping system of its own.

* OxygenMeter: Unaided, you can hold your breath for 45 seconds, and going below 100 meters without a Rebreather cuts that time in half. You can get tanks that will add to your air, but you can still run out if you're outside of a powered vehicle or station. If you lose power, you'll soon lose air there, too. Running out won't immediately kill you, though; you'll begin to black out when your meter runs down, and if you manage to get a gulp of air before completely losing consciousness, it'll revive you.

** Thalassophobia is the fear of the ocean -- and what might be lurking beneath it. It can be bad enough here on Earth. On an uncharted alien planet, where nothing is familiar and you know (with certainty) that Leviathan-Class {{Sea Monster}}s swim in the EldritchOceanAbyss, it's worse. If you don't see or hear them, it only means [[NothingIsScarier they are hidden]]... for now. You are utterly out of your depth and in over your head. ({{Pun}} intended.)

* ProductPlacement: The Cyclops is modeled after the class of submersible from the private deep sea exploration firm [=OceanGate=]; the company receive [[https://foone.tumblr.com/post/721234394948452352#notes a special thanks]] in the credits as a result.

* RegeneratingHealth: Your health recovers slowly but surely. It's more reliable when your hunger meter is above 100 (it goes to 120-130 at most).
* RespawningEnemies: The creatures of Planet 4546B eventually respawn. As of the full release, however, medium to large creatures no longer respawn, meaning it is possible to kill them all. Yes, this includes most Leviathans.

* ShownTheirWork: Before lead became a resource to find as any other (Machinery update), it was manufactured by combining copper and silver ores. This reflects the fact that lead can be found in ores of other metals, such as Galena (an ore of silver). However, for a while lead used to be manufactured from [[ArtisticLicense two batteries]].

* SuperPersistentPredator: Largely {{averted|Trope}}. Most predators will tend to avoid the player character unless an opportunity presents itself, and even then will tend to give up the chase if the player character can outrun them or proves themselves capable of hurting the predator (a good knife wound will often send the predator swimming away as fast as its fins can propel it.) On the whole, they tend to prefer easy prey. The closest thing that comes to playing this straight is the Reaper Leviathans, which seem to be apex predators. If one has spotted you, ''run''. '''''Run and don't look back.''''' Or, seeing as it can [[LightningBruiser outrun your Seamoth and also tear it to shreds in seconds]], [[YouAreAlreadyDead don't bother]].
** That said, the Seamoth Perimeter Defense system allows you a quick zap to minimize hull damage that will send Reapers the other way or a longer charged-up one that can outright kill smaller predators (including bone sharks). However, Reaper, Ghost and Sea Dragon Leviathans won't be discouraged for long by the shock.

** It's not obvious from the start that oxygen tanks actually store oxygen rather than merely increasing your cap. If you have several in your inventory, each has its own supply and can be swapped out as the equipped one depletes. Similarly, each individual tank must be refilled with air by equipping them.
** Also applies to the game as a whole. The vast majority of contemporary survival games have tutorials, quests, map markers (not to mention a map in the first place), a more or less strict narrative with a clear ultimate goal, and so on. ''Subnautica'''s total lack of any hand-holding can be baffling to new players until they switch their standard video-gaming expectations back to common sense and think about what anyone who's stranded within uncharted territory would do: survive the first day, come up with a plan to get the hell out of there, and then survive long enough to figure out how to do just that.

* UnderTheSea: Almost the entire game takes place in the ocean, with [[spoiler:a couple of islands]] and the non-submerged half of the ''Aurora'' being the only exceptions.

** If you die and aren't playing on [[PermaDeath Hardcore]], you're warped back to the last habitat you visited. If that death also involved the destruction of your vehicle, and your last habitat happens to be situated too deep to reach the surface by swimming and you don't have any resources close enough to build a new vehicle or a habitat builder to deconstruct your habitat and reset your spawn point to the original life pod, you're stuck there.

** You may also simply die of thirst or starvation on such excursions. The latter can usually be staved off by catching some edible fish, but if you don't have the Thermoblade (which cooks any small edible fish on contact), eating them raw seriously lowers your hydration, so you're dead anyway. Always make sure you have a healthy supply of food and especially water before you head out.

* VideoGameCrueltyPotential: The Bioreactor breaks down organic matter as fuel. ''Any'' organic matter. Innocent creature eggs? Into the reactor if you wish.

** At some point in ''Subnautica'', your AI assistant can remind you that everything you collect while stranded planetside belongs to the company by default, with a reminder that you will owe compensation for everything you use to survive. The message then provides an estimate of your running total which is at ''3 million credits'' [[spoiler:, and by the end of the game your total will have gone up to ''a trillion'']].

** Once you have the blueprint for a given piece of technology, you have to go to the appropriate [=fabricator/station/tool=] and spend the required raw materials to actually construct it.

* EnemyScan: One of the core tools is a scanner to scan just about everything, hostile fauna and flora included. The results of each completed scan are stored in the PDA, which therefore in part serves as a MonsterCompendium.

** There is a taming mechanic. Holding Peepers or other small prey fish in your quick slots will let Stalkers eat them, and they won't attack you. For a while. They even occasionally bring piles of scrap.
** It seems to work for Reaper Leviathans as well, as people have tried so and uploaded the results to youtube, but don't count on it saving your ass. Said videos feature an animation where the player raises their arms, and the screen goes black, but there's no You Died message. The Reaper removed all prey fish from your inventory and spat you out.

* EverythingIsAnIPodInTheFuture: All Alterra equipment is shiny white, with smooth surfaces and rounded edges and corners. Any larger sea base you build will inevitably look like an Apple designer's wet dream.

* EverythingTryingToKillYou: Averted, particularly in the [[MeaningfulName Safe Shallows]]: there are lots of passive fish which will never harm you at all, and also plenty of defensive fish who will only attack if you get too close or bother them. The truly aggressive species are actually a minority, but they're still almost omnipresent and extremely dangerous even so, seeing how even a single one can often kill you in a flash.

* FamilyFriendlyFirearms: Lethal firearms are forbidden from being created by the fabricator (something about a [[NoodleIncident massacre on Obraxis Prime]]). You can arm some of your submersibles with torpedoes, but the only true handheld weapon is the non-lethal stasis rifle.[[note]]There is also the survival knife and the propulsion/repulsion cannons, but these are more tools than weapons.[[/note]]

** The Titan Holefish has gotten so reliant on the small fish it shares a [[TheSymbiote symbiotic relationship]] with for food and defence that it's in a perpetual state of calm and seems to be barely aware of its surroundings.
* GiganticAdultsTinyBabies: The larger hatchable animals emerge from their eggs in the Alien Containment tank no bigger than a peeper, making even the likes of Crabsquids or Cryptosuchus look cute.
* GlowingFlora: Many deep-sea plants (this includes a ''tree'') are just as luminous as the rest of the living things there. This was probably to emphasize the abyssal aesthetic since many bioluminescent creatures inhabit this biome in RealLife. And because BioluminescenceIsCool.
* GratuitousLaboratoryFlasks: Several wrecks are strewn with nonfunctional lab equipment including microscopes, analyzers, and glass flasks. They are useless to you, but you can invoke this trope by taking them back to your base and [[AndYourRewardIsInteriorDecorating placing them decoratively]].

** The whole point of the Propulsion Cannon - a tool meant for picking up and moving/throwing small to medium-sized objects. Seeing how the thing is a barely disguised {{Expy}} of ''VideoGame/HalfLife2'''s Gravity Gun down to a very similar look, this shouldn't come as a surprise.

** Part of what makes ''Subnautica'''s survival atmosphere so intense is that you're told next to nothing upon starting a new game, and things barely improve from there on. There are no instructions, no tutorial, not even a friggin' ''map'', least of all something like a quest log (or even quests to begin with). The only real HUD markers you get are from the few other ''Aurora'' survivors, and that ends fairly quickly. Afterwards, you're completely on your own, and unless you consult a guide, you can spend hours upon hours getting lost in subterranean tunnel systems, wondering if there's even a point in risking your life down there and if there is, what you're supposed to accomplish in this place. [[Administrivia/TropesAreTools May sound bad, but]] it makes for an epic adventure full of astounding discoveries.

* HotBlade: The sole upgrade for the Survival Knife equips it with a heating element, causing the edges of the blade to [[PowerGlows glow red]]. This doubles its damage output (but [[spoiler:makes it useless against heat-resistant wildlife]]), and [[MundaneUtility it can kill and cook edible wildlife in one strike]].

* InVehicleInvulnerability: You can't be hurt (except by hunger or thirst) when you're inside any vehicle or base. While head-on collisions might damage your vehicle, you'll never be knocked unconscious by flying shrapnel like in the opening cinematic. And then subverted to hell and back by the [[{{Cyborg}} Warpers]], which have the ability to teleport you ''out'' of your vehicle so they can attack you.

** At some point in ''Subnautica'', your AI assistant can remind you that everything you collect while stranded planetside belongs to the company by default, with a reminder that you will owe compensation for everything you use to survive. The message then provides an estimate of your running total which is at ''3 million credits''[[spoiler:, and by the end of the game your total will have gone up to ''a trillion'']]. Maybe surviving the crash wasn't such a stroke of luck after all...
** The revamped sequel story starts with Robin jetting down to the surface of 4546B to look for her sister Sam. One of the log entries she starts out with is a death notification for Sam that mentions legal services will be calling soon to transfer all open debts that Sam had accumulated to Robin to be paid off.
* ContinuingIsPainful: When you die (on anything but the hardest difficulty, which features PermaDeath), you're teleported back to your last habitat or life pod and any items you picked up since then are lost. If you died a death moments after stepping outside your pod, not such a big deal, but if you've spent several minutes swimming to and fro and gathering resources, it can be quite exasperating. In the worst scenario, you've lost your vehicle during your trip and are warped back to a seabase too deep to reach the surface without aid.

* CrapsaccharineWorld: Humanity is far advanced, has explored and controls most of the galaxy and can make nearly anything with their extensive replicator-like technology. Yet all of it is controlled and maintained by {{Mega Corp}}s and humanity basically lives in a strict capitalist/contractual mindset where even something as simple as a boyfriend/girlfriend relationship requires an extensive contract agreement!

* {{Cyberpunk}}: Not too obvious because it doesn't look the part and only becomes apparent if you [[AllThereInTheManual read all the PDA entries you pick up]], but the world of ''Subnautica'' is a hellish hyper-capitalistic dystopia. Mankind has developed amazingly advanced technology, yet at the same time, their society has degenerated into an utter nightmare. Charity has officially been declared obsolete in favour of an objectivist mindset that would make Creator/AynRand weep with joy. Everyone is on their own and only out for themselves. {{Megacorp}}s rule their interplanetary domains like nation states without any obligation to treat their employees/citizens like people instead of just assets. Possibly worst of all, even the most private matters like interpersonal relationships and love have been turned into cold business contracts that can (and are encouraged to) be unilaterally changed or terminated whenever any of the "business partners" feels mildly dissatisfied with the state of affairs, feelings of their partner be damned.

* DeathIsASlapOnTheWrist: In every mode except hardcore, upon being killed you simply respawn in the last habitat you left, with full health and the entirety of your inventory when you were there last intact. All you lose is what you might have picked up in the meantime. It's such a cheap death that if one's health is low, instead of bothering with health kits a perfectly viable technique is to build a basic habitat tube, a hatch, get in, get out, die intentionally and respawn in the habitat you just created with your health restored. Deconstruct the habitat and go on your merry way.

** Thermal Plants. The fragments needed to obtain their blueprints are difficult to find (most abandoned bases are nuclear-powered), they use rare components, and can only be built over high temperature sources, most of which generally aren't near where you build your base unless you go out of your way to do so. All that said, Thermal Plants have an advantage no other power source does: no upkeep. Once built, they provide a constant stream of energy that doesn't need to be refilled (Bioreactor, Nuclear Reactor), nor does it deactivate periodically like Solar Panels. If placed on a spot with a temperature greater than 60° C, they outperform everything but Nuclear Plants, and you can generally fit several in the same area to take advantage of the hot spot. In addition, the need to build your base near a high-temperature spot can easily be circumvented by building some Power Transmitters to link your thermal plants to your base. Three or four will generally power pretty much any activity you engage in, even high-intensity operations like water filtration.

** The Seamoth mini-sub is the first true vehicle you'll probably unlock in ''Subnautica''. While it lacks the PRAWN's utility and sturdiness, it's quite fast, reasonably cheap to build and extremely manoeuvrable even in tight spaces. It boasts decent storage capacity for something so small and can even be equipped with up to four torpedo launchers. Its utility upgrades are also quite helpful against anything including Leviathans. Until the story absolutely forces you to descend to depths below the Seamoth's maximum upgradable crush depth of 900m, the little fellow is generally a much more convenient exploration tool than the huge, supremely unwieldy and very expensive Cyclops, or the PRAWN with its serious trouble in getting out of deep-sea trenches without some expensive upgrades. The same can be said for the Seatruck without any modules in ''Below Zero''.
** Beacons are little gizmos you can drop in the water to mark points of interest - an invaluable asset in a game that lacks a map or any other waypoint system. They're cheap to build, their blueprint is easy to find, they only take up a single inventory slot, and they can even be given individual names to help you keep track of what's what. You can toggle which ones are visible from anywhere, to avoid UI clutter. New players should never leave base without one or two beacons in their pack, especially in the early game stages when you're still discovering new stuff around every corner, but they remain very useful throughout the whole game. That they look suspiciously like [[VideoGame/{{Portal}} Aperture turrets]] is just icing on the cake.
** The Swim Charge Fins slowly recharge the battery of your currently held tool, but don't grant any increase in speed. However, the recharge rate exceeds the battery drain of the Seaglide, so using them allows infinite use of the Seaglide and makes the speed penalty meaningless.
** Of all the things you can build in/around your base, perhaps the most useful is the humble growbed. At a mere four titanium, the growbed allows you to grow most kinds of flora at your base without having to travel to their natural habitats, in greater quantities than you're likely to find in the wild. Home-grown flora doesn't damage you if it would otherwise (acid and deepshrooms) and sometimes produces more resources than a wild plant (creepvines). Hunting down fish for food becomes almost unnecessary when you can grow marblemelons or bulbo trees inside your base and harvest them periodically, and you can even stick one in your Cyclops for food on the go.

* CheckpointStarvation: There are no checkpoints. Each game only has a single ''manual'' save slot and nothing else. Dying warps you back to the last habitat you visited, but that's about it. Be very careful about when, where and under which circumstances you save your game, or you might realize too late that you trapped yourself in a dead end with no way out, not even by reloading. If your computer has a habit of crashing (which is likely given Subnautica's less-than-optimal code) save every time you unlock a new blueprint or find a rare mineral because computer crashes will delete all your work.

* BlackHumor: The game has a rather grim sense of humour. Special note goes to the PDA descriptions, which range from poking fun at your current situation to relaying horrific information in a matter-of-fact way. [[spoiler:Which ultimately culminates in the BrickJoke / YankTheDogsChain that is TheStinger, as detailed under those entries below.]]
* BlownAcrossTheRoom: The Repulsion Cannon packs an impressive wallop for something so small. It doesn't deal much damage, but the force it applies is sufficient to push even the largest non-Leviathan beasts back several dozen meters. Smaller creatures like Stalkers turn into a TwinkleInTheSky when shot from below in shallow waters, and it can take quite some time before they fall back into the sea. The PDA describes it as a non-lethal weapon even though realistically such force would cause fatal trauma and it and the Propulsion Cannon can be used to kill smaller creatures by slamming them into walls.
* BodyHorror: The Kharaa bacteria not only affects the immune system, but it also alters the host's [=DNA=] and changes their body structure, most notably, it causes green glowing pustules to grow all over an infected individual's body.

* BlackHumor: The game has a rather grim sense of humour. Special note goes to the PDA descriptions, which range from poking fun at your current situation to relaying horrific information in a matter-of-fact way. [[spoiler:Which ultimately culminates in the BrickJoke/YankTheDogsChain that is TheStinger, as detailed under those entries below.]]

* BlackHumor: The game has a rather grim sense of humour. Special note goes to the PDA descriptions, which range from poking fun at your current situation to relaying horrific information in a matter-of-fact way. [[spoiler:Which ultimately culminates in the BrickJoke cum YankTheDogsChain that is TheStinger, as detailed under those entries below.]]

** The Nuclear Reactor is the most powerful reactor in the game, having both energy output and reserves four times greater than any other form of power generation. A single one can power virtually any activity by itself. It's also the most resource-intensive, requiring significant amounts of uranium and lead for the fuel rods that keep it running, as well as producing spent fuel rods as a byproduct, something no other generator does. If you're willing to build up a large stock of materials, you never need to worry about power, but the other generators either require no upkeep (solar, thermal) or merely a steady supply of breedable fish from an Alien Containment (bioreactor). Subsequent patches significantly upped the total energy value of reactor rods to alleviate this problem, allowing a Nuclear Reactor to run at a full draw for five hours straight before it needs to be refilled. To put that in perspective, a single reactor rod has double the energy potential of a Bioreactor fully stocked with Oculus as fuel, and generates power five times as fast.
** There's no doubt that the Cyclops is awesome, but it's also large and unwieldy, which can make it difficult to navigate many of the tight deep sea cave systems it's meant to explore. This isn't helped at all by the multiple Leviathans down there that it can't outrun as it could in open waters, meaning you'll have to be ready to make repairs on the fly while surrounded by scorching temperatures and hostile fauna. Veteran players with intimate knowledge of the cave layouts and entry/exit points may have an easier time, but an upgraded PRAWN suit is much more versatile when it comes to exploring the game world's deepest reaches. It also isn't easy to keep charged, as it can't be docked at a Moonpool and runs on six Power Cells. The thermal charging upgrade can only be built after reaching the deepest depths, and it doesn't do much good on the surface unless you parked your base near a surface vent. Unfortunately, [[AbilityRequiredToProceed you must build a Cyclops]] at some point to gain access to the Cyclops Shield Generator tech, which you need to [[spoiler:complete the Neptune Rocket and finish the game]].

** The Observatory is the only seabase module that is purely ornamental and thus does not serve any actual purpose beyond stationary sightseeing. Watching the sea around you while safe from harm is certainly cool, but the average player will be much too busy exploring and surviving to do this on a regular basis. This, coupled with the Observatory's disproportionately high impact on hull integrity, makes it something of a luxury addition to well-armoured bases in well-lit areas that are rarely worth its cost. The PDA actually lampshades this in its item description.

* BizarreAlienBiology: Everything!

** The brine in the Lost River is GrimyWater which is as caustic as acid; merely skirting it while swimming around the area deals considerable damage. Brine in RealLife has no detrimental effects on the human skin no matter the concentration[[note]]unless you marinate yourself in it for a ''very'' long time; we're talking multiple hours here, which may lead to dehydration[[/note]], much less so if the swimmer is clad in full-body diving gear. Brine baths have actually been used for medicinal purposes since time immemorial, mostly to treat various skin diseases.
*** "Brine" is probably just a placeholder (Seeing as the PDA uses LineOfSightName conventions), Acid Salts are an actual thing, it may be a high concentration of Acid Salt, which would explain the burning.

** Many of the fabricator's recipes don't exactly add up. For example, polyaniline is a real substance, but gold has nothing to do with its synthesis.
* ArtisticLicenseEngineering: Seabases do make ''some'' concessions to the needs of an underwater habitat; too much stress on the hull causes it to buckle, and depth directly correlates to the amount of stress exerted. However, [[AcceptableBreaksFromReality for simplicity of gameplay]], hull stress is calculated based on the totality of the structure, rather than individual pieces. Each piece has a positive or negative hull value that adjusts the initial value of 10. As long as the value stays above 0, hull integrity is secure. Structures like the Moonpool or the observation dome significantly subtract from hull value, but simply slapping some lithium-strengthened reinforcement panels to any other part of the seabase will more than compensate for it.

* ArtisticLicenseSpace: The [[AlienSky two moons of the planet]] are in an extremely low orbit judging by their size and the speed at which they cross the sky. The gravity from Earth's moon causes a daily high and low tide at a much further distance out. Two moons of that size and proximity would cause titanic and unpredictable waves, with fluid forces that would make movement and navigation almost impossible. Instead, the planet has a very calm ocean and the moons simply form a very pretty sky and a major light source at night.

** Decompression sickness is not an issue in this game. Given that the protagonist can only stay underwater for 45 seconds (plus 30 seconds more for each air tank at the cost of speed and inventory space) it would be a little much to require you to wait an hour each time you needed to ascend 30 meters. You can toggle on decompression sickness by entering '[[spoiler:nitrogen]]', but that is through the command console. You can also enter and leave vehicles/seabases at will without worrying about pressure differences. It is assumed that the hermetically-sealed All-Environment Protection (AEP) Suit compensates for this sudden pressure change, given how it's the first piece of equipment utilised in the event of a [[ExplosiveDecompression starship hull breach]].

** Hatches to get in and out of seabases and alien containments are a single porthole rather than an airlock. Moving around would be greatly hindered if you had to wait each time or, in the case of the alien containment, be blocked off on one side of the room by the extra space needed for the airlock. Just assume that the porthole also generates a specialized force field to keep water out somehow and don't think of it any further.

** You can't improve a vehicle’s crush depth by hundreds of meters via what is essentially chip tuning. An upgrade like this would require extensive redesigning and strengthening of the hull at the very least. The same goes for installing torpedo tubes or miniature storage lockers (expansions). Both options are lumped in with all the other performance upgrades for the sake of providing one streamlined game mechanic (although it would've been nice to have some visual change to the hull at least when crush depth and hull reinforcement modules are installed). Assume that the upgrades utilize fabricator technology to reconfigure your vehicles, and don't think about it too much.
** Light, and with that, colour doesn't travel very far through the water. Long wavelengths such as red are the first to be cancelled out. For gameplay purposes and a pretty game world, this is ignored.

** Although it can come across as seriously immersion-breaking for some, the PlayerCharacter's invulnerability to water pressure is mostly a welcome feature[[note]]Unlike the three vehicles, which have specific crush depths, Ryley can dive as deep as he wants without ill effects (aside from increased oxygen consumption, though that can be quickly mitigated through the use of a Rebreather), and he can leave vehicles at any time no matter the depth[[/note]]. The game is unforgiving enough as it is without you being unable to repair or, if need be, AbandonShip if push comes to shove.

** After the player begins building vehicles, they will have to craft more advanced depth modules for them to prevent the vehicles from being crushed by water pressure in deeper waters (strangely, the worst that will happen to the player in terms of how deep they go is how much oxygen they use, and even that is negated with a rebreather).
** The crash site of the ''Aurora'' in ''Subnautica'' is blanketed with radiation leaking from breaches in its reactor shielding and can only be approached safely if wearing a suit lining rated for radiation resistance; as the area around the ship has the highest density of debris, building the radiation suit is an important step. In addition, certain parts of the ship require either a laser cutter, propulsion/repulsion cannon, or a repair tool to enter. Entering the ship allows you to fix the radiation leak, which negates the need for the radiation suit after you've done so and allows you to use better suits and the rebreather in the same area. A number of the smaller wrecks also require some of these tools to explore them. You're forced to wait until after the ''Aurora'''s drive core explodes before you actually get the radiation suit blueprints, though, which does allow you time to prepare for the journey and find the materials needed to craft it beforehand.
** In ''Below Zero'', the new thermal system requires you to manage your temperature when exposed on land. Certain heat-generating plants, warm caves and sulfur pools all offer respite from the cold. There's also a number of consumables (coffee, for example) that restore temperature and cold weather gear that helps retain heat. Conversely, adverse weather on the surface causes heat to dissipate faster.

** Even in the full release, vertical seabase modules are still somewhat buggy, and one particular bug has been in the game a full three years before going gold. Sometimes, if you construct a tunnel compartment, place a vertical module on top, put a Multipurpose Room on top of that, and then try to install a ladder so you can access the Multipurpose Room from the lower compartment, the entire three-module section will sometimes bug out, not allowing the installation of a ladder nor the deconstruction of any of the three modules. Both the compartment and the Multipurpose Room can still be entered, and used, and have some compartments attached to them, but the vertical compartment remains useless, and if you plan on changing up your base, you're out roughly 16 Titanium and have to be willing to either move or work around the stuck modules. ** Sometimes when you drop something, it falls through the floor. This can be quite irritating, especially if it was a useful piece of equipment.

** Even in the full release, vertical seabase modules are still somewhat buggy, and one particular bug has been in the game a full three years before going gold. Sometimes, if you construct a tunnel compartment, place a vertical module on top, put a Multipurpose Room on top of that, and then try to install a ladder so you can access the Multipurpose Room from the lower compartment, the entire three-module section will sometimes bug out, not allowing the installation of a ladder nor the deconstruction of any of the three modules. Both the compartment and the Multipurpose Room can still be entered, and used, and have some compartments attached to them, but the vertical compartment remains useless, and if you plan on changing up your base, you're out roughly 16 Titanium and have to be willing to either move or work around the stuck modules.
* GameplayAndStorySegregation: An important factor in what happened to one group of survivors from the ''Aurora'' was how they tried to cope with extreme weather conditions. You never encounter anything but calm weather during gameplay.
** Sometimes when you drop something, it falls through the floor. This can be quite irritating, especially if it was a useful piece of equipment.

''Subnautica'' is an open-world {{Science Fiction}} survival game developed by Unknown Worlds Entertainment, creators of the well-received ''VideoGame/HalfLife1'' mod ''VideoGame/NaturalSelection'' and its sequel. Having spent almost four years in Early Access, and with its V1.0 deadline pushed back five times - from September 2016 to January 2017, then to February 2017, then to May 2017, once more to September 2017, and finally to 2018 - the game has fully launched on PC as of January 23, 2018. It receives one stable update per month and regular small updates for people who play in experimental mode. The game is available for the PC, Xbox One, Mac, [=PS4=] and Nintendo Switch.

* ObviousBeta: Even with the rest of the game functioning fine, the ''Aurora'' remains are blatantly this. It's full of a bunch of arbitrary invisible walls that make traversing it more of a maze than it already is, and it has a number of textures that you can just swim right through.

** Of all the things you can build in/around your base, perhaps the most useful is the humble growbed. At a mere four titanium, the growbed allows you to grow most kinds of fauna at your base without having to travel to their natural habitats, in greater quantities than you're likely to find in the wild. Home-grown fauna doesn't damage you if it would otherwise (acid and deepshrooms) and sometimes produces more resources than a wild plant (creepvines). Hunting down fish for food becomes almost unnecessary when you can grow marblemelons or bulbo trees inside your base and harvest them periodically, and you can even stick one in your Cyclops for food on the go.

** Several new structures are added to make base building more convenient. A control room can be built that can manage which rooms are drawing power, shows how much power is being generated/consumed, and helps you locate damaged sections. It also acts as a beacon, instead of having to drop one yourself. There's also the addition of large rooms, allowing you to consolidate certain functions like power generation that would ordinarily require an entire Multipurpose Room per reactor, or just make more elaborate habitats. The latter was ported back into ''Subnautica''.

** The Nuclear Reactor has, at minimum, four times greater output than any other form of power generation, allowing it to power virtually any activity by itself. It's also the most resource-intensive, requiring significant amounts of uranium and lead for the fuel rods that keep it running, as well as producing spent fuel rods as a byproduct, something no other generator does. If you're willing to build up a large stock of materials, you never need to worry about power, but the other generators either require no upkeep (solar, thermal) or a steady supply of breedable fish from an Alien Containment (bioreactor). Subsequent patches significantly upped the total energy value of reactor rods to alleviate this problem, allowing a Nuclear Reactor to run at a full draw for five hours straight before it needs to be refilled. To put that in perspective, a single reactor rod has double the energy potential of a Bioreactor fully stocked with Oculus as fuel, and generates power five times as fast.