Videogame / Subnautica

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Subnautica is a survival game developed by Unknown Worlds Entertainment, creators of the well-received Half-Life mod Natural Selection 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, and Mac, with a PS4 port planned for after V1.0 because the PS4 has no Early Access program.

The game is set on an alien ocean world, designated Planet 4546B. The player is the 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 bases 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.


Subnautica contains examples of the following tropes:

  • Abandoned Area: The various abandoned bases. The Sparse Reef also invokes this when the PDA questions why it barely features any life.
  • Ability Required to Proceed: Many areas are, if not impossible, at least extremely impractical to access without the right equipment. For example, the crash site of the Aurora 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. Certain depths are difficult to plumb without sufficient oxygen reserves and a rebreather or a vehicle rated to withstand the pressure at that depth. Some items and fragments are locked behind doors that need to be cut open with a laser cutter, etc.
  • Abnormal Ammo: Stock in trade of the Propulsion Cannon, which can lob anything you care to load into its energy field at considerable velocity. With nerves of steel (or an Alien Containment and some patience), it can harness the explosive power of the Crashfish into a formidable weapon.
  • Absurdly Sharp Blade: The survival knife, which can cut through solid pieces of coral like butter.
  • Acceptable Breaks from Reality: Several.
    • Decompression sickness is not an issue in this game. Given that the protagonist can only stay under water 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 also enter and leave vehicles/bases at will without worrying about pressure differences. Assume the suit compensates somehow and call it a day.
    • Hatches to get in and out of bases and tanks 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 tanks, be blocked off on one side of the room by the extra space needed for the airlock.
    • Diving speed in real life is slowed down by arm movement, but the protagonist uses their arms constantly. This is done to give the player better visual feedback.
    • Light, and with that color, doesn't travel very far through water. Long wavelengths such as red are the first to be cancelled out. For gameplay purposes and a pretty gameworld, this is ignored.
    • The two moons of the planet are in an extremely low orbit judging by their size and the speed that 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 major light source at night.
  • Action Bomb: The Crashfish, a fish that explodes to damage the player.
  • Action Prologue: The game opens with the Player Character strapping into a lifepod to a cacophony of alarms, with no knowledge of what's going on except that it's time to Abandon Ship. Once you've made planetfall and put out the fires in the pod, you can finally take a breather and start planning your objectives.
  • Adaptive Ability: The lifeforms of 4546B are implied to evolve at a much faster rate than earth lifeforms as according to the PDA many of the current organisms developed in just the last thousand years, something that would take millions for earth creatures.
  • Adventure-Friendly World: A couple of common survival blueprints are not available to the protagonist because their PDA files have become corrupted. Fragments or examples of the items need to be found and scanned before they become available for construction.
  • Alien Blood: Originally averted, but now played straight, with the planet's creatures having yellow blood.
  • Alien Sky: There are two moons in the sky, one of which is extremely large, resembles Mars, and often causes solar eclipses.
  • All Flyers Are Birds: Zig-zagged; the only flying creature you see looks for all the world like a flying manta ray, but the scanner says that its "fins" are actually composed of oddly-shaped feathers.
  • All Planets Are Earthlike: Although this one has water covering nearly its entire surface, as opposed to a measly 70% of it.
  • The Alliance: PDA entries mention the Trans-System Federation, which exists as an authority above the Trans-Govs, of which Alterra is one. According to the Charter, the TSF exists as a military police force dedicated to preventing conflict among its members and guaranteeing relative freedom of movement within its borders. Said Charter is why the Sunbeam is obligated to respond to the distress call from the Aurora, and thus what gets them killed.
  • Almost Out of Oxygen: There is a high possibility of this occurring while harvesting resources or trying to escape danger.
  • Amazing Technicolor Wildlife: The fish in the game are really colorful. At night many light up in all kinds of bioluminescent colors.
  • An Interior Designer Is You: When it comes to basebuilding. Overlaps with And Your Reward Is Interior Decorating because you need to scan most pieces of furniture before you can build them.
  • Apocalypse How: The Sea Dragon Leviathan's attack on the Secondary Bio-Research Facility in the Lost River released the Kharaa bacterium onto the planet. The gigantic crater in which Subnautica takes places is the only location on the entire planet where any life remains, thanks to the Sea Emperor Leviathan distributing small doses of the enzyme that gives it its immunity through Peepers and the Alien vents. Kharaa most likely culminated in a Class 1 or 4 for the local fauna. And this is a mere drop in the bucket, given Kharaa wiped out about 143 billion individuals on Precursor worlds.
  • Apocalyptic Log: While the Aurora's initially-inaccessible black-box recorder doesn't quite count, as of the farming update, you can discover what remains of another crash-landed crew's seabases, which includes an abandoned PDA from the captain, Paul Torgal, who unsuccessfully tried to call for help. The AI informing you that the way that the Aurora's drive core exploded was not caused by the crash itself, the circumstances of Paul's crash and the contents of an un-implemented log heavily implies that the Aurora's crash was not a freak accident. Later builds of the game allows you to witness what happened firsthand when the Sunbeam gets blown up by the Precursor Gun while trying to rescue you, although this time there's no crash and no survivors.
  • Artistic License – Astronomy: The aforementioned twin moons.
  • Artistic License – Engineering: Seabases make some concessions to the needs of an underwater habitat, requiring structural reinforcement to not fall over or apart, and the lower a seabase is built the higher the water pressure on it and greater the reinforcement required. However, for simplicity of gameplay, the reinforcements and weaknesses have nothing to do with one another. The game simply totals up the "strength" value of certain parts and subtracts the "weakness" value of other parts, and so long as they balance out the base is stable. An observation dome might be a major weak point, but slapping some lithium-reinforced panels on a moonpool on the other side of the base will more than compensate for it.
  • Attack Its Weak Point: Not a gameplay trait but a programming trait. Very large creatures do not have a full-body hitbox and something like the Stasis Rifle won't affect them if they're hit where they don't tangibly exist. This is especially true for the Reaper Leviathan, which despite its size only counts for its head. You can swipe ineffectually at its tail, but you'll only get hit noises and blood fx spawning near its head.
  • Audible Gleam: When you pick up gold or diamond.
  • Bio-Augmentation: What the Transfuser does. It's temporary, though.
    • The Transfuser isn't in the full 1.0 release, but it's gonna be implemented sometime in the future.
  • Bioluminescence Is Cool: During the night and the underwater cave sections, certain fish and plants will have a luminescent glow. This will help you see where you're going. This is especially prominent in the Jelly Shroom Caves, Bulb Zone, and Grand Reef, thanks to their massive glowing flora.
  • Bizarre Alien Biology: Everything! Special consideration goes to the Ampeel for its electro-spikes all over its body, the Gasopod for both its gasmask face and tail-sack, the Reaper for its face clamps, the Sea Treader which uses its snout as its third leg, and the Crabsquid for its everything.
  • Bizarre Alien Sexes: Everything on the planet is of a single egg-laying sex that can either self-impregnate or mate with any other instance of its species.
  • Black Humor: The game has a rather grim sense of humor. 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. Which ultimately culminates in the Brick Joke cum Yank the Dog's Chain that is The Stinger, as detailed under those entries below.
  • Border Patrol: Adult Ghost Leviathans spawn in the Void/Crater's Edge, with even the PDA saying exploring said biome is "not recommended." At sufficient distance if you somehow survive, you'll allegedly be teleported to Lifepod 5.
  • Bothering by the Book: Alterra is apparently quite guilty of this In-Universe, given Captain Avery Quinn's complaints about them. Under the terms of the Trans-Gov charter, ships are obligated to investigate and respond to any distress beacon they come across, with harsh penalties for failing to render aid. Alterra ships have developed a reputation of abusing this to get other people to give them utterly non-essential supplies if they run out.
  • Brick Joke: Early in the game, the PDA explains that everything on the planet is property of Alterra and that you will be billed for everything you used, with the bill running at three million credits. Come the Stinger after the credits roll, You have made it back safely, but Alterra refuses to allow you to land your rocket until the debt you owe for the resources used on 4546B is paid, which is now at a grand total of a trillion credits.
    • On said escape rocket, upon exiting atmo you enter a debris field from the Aurora. A panel breaks off and the protagonist raises their hand defensively, having learned about getting smacked in the face by loose panels from the prologue.
  • Chekhov's Gunman: The player character, of all people. Go figure that the Precursors failing to get rid of him at the beginning wound up saving their planet in the process.
  • *Click* Hello: The Crashfish make a sound that sounds a lot like this when popping out of their nests. The chase noise they have can be best described as a gurgling rising in pitch until it goes boom.
  • Cloning Body Parts: New organs and the like are a regularity for people who have the money for it in the future world of Subnautica. A guaranteed supply is one of the perks of Alterra higher-ups and as Paul Torgal says: "I turned 80 years old last week. I thought I had another 80 in me yet. Stuck here, there's no swapping out my liver when the old one fails. Down here, I'm mortal."
  • Colony Drop: A meteor fell on Planet 4546B in the Dunes 1,000 years ago, which is implied to have had long-lasting effects. The PDA implies that the meteor is what started the extinction event on the planet. The Kharaa only made it worse.
  • Company Town: Downplayed. Some of the info you can download from PDAs highlights the Mega Corp. nature of Alterra, who are so big that they practically constitute a form of government. At some point in the game, 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. Maybe surviving the crash wasn't such a stroke of luck after all....
  • Continuing Is Painful: When you die (on anything but the hardest difficulty, which features Perma Death), you're teleported back to your last habitat 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 base too deep to reach the surface without aid.
  • Convection Schmonvection: Downplayed. There are volcanic vents which have frequent outbursts of hot water and rock fragments. These can't hurt you, but getting too close (as in right next to the glowing crater) will cause you to take heat damage. It should also be noted that according to in-game temperature readings, it isn't even that hot — harmless Thermal Vents tend to be hotter even in the Lava Zone than the bright red, damaging craters (vents spiking to 80 C or higher, while some harmful and seemingly hot spots may be as low as 50 C).
  • Cool Boat: All of the craftable ships, but the crown of this trope goes to the Cyclops submarine, which is also a mobile base for the player.
  • Cool Starship: The Aurora, which ends up exploding, giving you entry, and placing a burden on you to repair the reactor containment field, or else you'll be overrun by deadly radiation.
  • Crate Expectations: Mostly stuff from the Aurora. You need a Propulsion Cannon or Repulsion Cannon to move them out of the way. Storage crates can be manually opened for goodies.
  • Creature-Breeding Mechanic: You can breed fish as long as you have two to start with and an alien containment unit to place them in. This is useful to create a steady food supply or a steady bioreactor fuel supply.
  • Crew of One: In-Universe, a selling point for the Cyclops is that, despite being designed to have an optimal crew of three, the whole vessel can be operated by a single person if the need arises. This has made it very popular among deep sea exploration teams, and is a tremendous boon for the player.
  • Critical Research Failure: In-Universe. The Precursors have been trying to hatch the Sea Emperor's eggs for centuries (especially since they need them to peacefully cure the Kharaa and stop having to resort to, you know, genocide). It turns out that the eggs aren't being raised in an environment meant for babies, and that the incubators they were placed in had their environment configured for what adults would inhabit. As such, it takes the player (again) to fix this. Truth in Television as in Real Life most giant sea creatures do, in fact, have different ideal living conditions as larva or juveniles before moving to the ones they prefer as an adult. Even worse, the Sea Emperor was trying to explain this to them, but they were deaf to her telepathic communications. Thankfully, Ryley is not, and can be instructed on how to get them to hatch.
  • Curb-Stomp Battle: Since the only damage dealing weapon in the game is your puny little knife, a confrontation with any hostile creature larger than yourself will almost inevitably be this. Your only real option is to flee.
  • Deadly Gas: Gasopods can produce gas pods that explode after a short while to create a deadly, yellow-green cloud. If the player is quick, they can grab one or two pods before explosion and use them in torpedos.
  • Deflector Shields: An upgrade for the Cyclops gives you one. The bubble effect only covers the forward canopy, but the effect is around the entire sub. It zaps Lava Larvae, renders the sub invulnerable to damage from even a persistent Sea Dragon, and also seems to prevent pressure crushing the hull. Too bad it drains power like nobody's business. It's required to build the Neptune Escape Rocket, as it allows you to survive the orbital debris field.
  • Derelict Graveyard: The volcanic crater/plateau that the Aurora crashed on is one, albeit it only consists of a single ship. Most of the Aurora landed in a large wreck that looms partially above the water, but large sections of the ship detached either during its fall or on it's impact, sending entire deck assemblies scattered about the ocean floor. Many of these still have their interior compartments relatively intact, and salvaging them is useful for basic supplies and essential for unlocking additional blueprints.
  • Developers' Foresight: If, by some absolute miracle (or use of console commands), you manage to shut down the Quarantine Enforcement Platform before the Sunbeam arrives, not only will the ship not be shot down, but Captain Quinn will send you a unique message about being unable to penetrate the immense orbital debris field left behind by the attack on the Aurora.
  • Difficult, but Awesome: The Cyclops and PRAWN. They are essential for the depths of late game where the Seamoth can't go, pack a punch, and have high customization options. They are, however, also slow and bulky and energy-draining, lacking the scouting qualities of the Seamoth. Specifically, compared to the 360 degree mobility, the Cyclops handles like a supermarket trolley, and the PRAWN suit - whilst boasting impressive armor - has little to no vertical maneuverability, making it easy to jump off an edge and spend a lot of time crawling back up.
  • Dishing Out Dirt: More or less the purpose of the Terraformer before it was removed for technical and gameplay purposes.
  • Doomsday Device: While exploring the Island Base, you can scan a malfunctioning one. Despite being small enough to hold in your hands, the data readout indicates it packs enough oomph to destroy the entire solar system.
  • Dummied Out: Occasionally you can see ideas from earlier Early Access builds floating around in the 1.0 release.
    • One of the first major things removed and mourned by the playerbase and the developers alike was the Terraformer. Ultimately, as the story developed from a vague "make this planet inhabitable" plot to a "escape the planet" one, the Terraformer was deemed unnecessary. Amusingly following the trope, players who carry over really old Early Access saves using the Terraformer retain the chunks of land that are missing or added to their game — sometimes regretfully, as the map has been updated since 1.0 and some players have bases inaccessible due to new land formations.
    • There was a plot at the end of the game for the Warpers to fight against the native wildlife in an Enemy Mine situation as the player, upon reaching the Sea Emperor, would be attacked by multiple Warpers at once trying to eliminate all infected life, but this plot fell through. Warpers are now mostly roaming deterrents that, while automatically attacking infected wildlife and getting attacked by territorial creatures, don't really coordinate their efforts.
    • As of the 1.0 update, the Thermometer is still in the Blueprints, but can't be built.
  • Dying Alone: The protagonist is at risk of this. From data downloads, it is known or implied that this has happened to almost everyone who didn't die in the crash.
  • Earn Your Happy Ending: For both the player and the mysterious race known as the Precursors. In the player's case, after fighting through a world full of dangerous creatures and leviathans, being infected to an advanced stage of The Plague, and losing a trade vessel in their sake, they construct a rocket and escape. For the Precursors, although they lost the one thing that they really wanted to protect, it brought forth a new generation of Emperors that will produce the enzymes necessary to finally cleanse the planet of the bacteria, and will soon no longer have the need to shoot down any more ships.
  • Easter Egg: A Natural Selection 2 poster can be found inside an explorable Aurora compartment in the Grassy Plateaus. You can even pick it up and hang it in your base.
  • Effortless Achievement: The full release still has a few of these. Getting your feet wet and consequently building your first base piece, which takes a little effort. You'll unlock achievements for building the three currently implemented vehicles and exploring story required locales. though they seem to be bugged, building the escape rocket and launching the time capsule also are achievements. The Neptune is pretty resource heavy but the time capsule is literally a button press to launch, and usually launches automatically with the rocket's ignition.
  • Enemy Scan: 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 Monster Compendium.
  • Equipment Upgrade: There's a modification station, a vehicle modification station, and two specialized fabricators to improve your stuff.
  • Enemy Mine:
    • Different species of predators are just as likely to territorially attack each other as they are to attack you. This is especially visible in the second Degassi seabase, where Warpers and Crabsquids will fight over the exclusive right to harass you while you're exploring it.
    • 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, the screen goes black, but there's no You Died message. The Reaper removed all prey fish from your inventory and spat you out.
  • Everybody's Dead, Dave: By the time the main game's events begin, every mentioned character except the player and the Sea Emperor, who is the Last of Their Kind after an incident which left 314 specimens of her species dead are dead or missing.
  • Everything Trying to Kill You: Averted, particularly in the 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 relatively rare.
  • Exactly What It Says on the Tin: The scanner data for the pink mushroom describes it as "definitely a mushroom". Most of the names of the fish are pretty descriptive as well; the Boomerang indeed just looks like a boomerang.
  • Family-Friendly Firearms: Lethal firearms are forbidden from being created by the fabricator (something about a 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 
    • The only true firearm is an alien rifle suspended in an impenetrable display case within the Quarantine Enforcement Platform.
  • Fastball Special: Any creature caught and flung by the Propulsion cannon, pair it with tank-grown Crashfish for explosive results.
  • Final Death Mode: Hardcore mode. Exactly like Survival mode, except you only have one life and have no oxygen warnings. Forget to check your meters at your own peril.
  • First Person Snapshooter: Optional. Pictures taken can be used as decoration in one's base by means of the Picture Frame.
  • Fluffy Tamer: The secondary function of the Alien Containment module, as any predator you hatch inside it will be docile towards you. This continues to apply if you release them from the tank and they become full grown. Ever wanted a pet Ampeel, Crabsquid or Boneshark? Now's your chance.
  • Friend to All Living Things: The Sea Emperor. She's entirely harmless, the normally predatory species living in her enclosure are peaceful, and she's actively trying to fight the infection of the planet.
  • Forbidden Zone: A few would qualify, but the Crash Zone is a prime candidate. Reaper Leviathans hunt in the surrounding seafloor, and after the Aurora's reactor containment field explodes, the area fills with radiation and cannot be explored without a radiation suit.
    • Then there's the Crater's Edge, AKA the Void, aptly named because the seabed steeply dives into an inky abyss and it's populated by multiple Ghost Leviathans who want nothing more than to eat you and your Cyclops.
  • Foreshadowing: You'll encounter small pink creatures called Floaters who have attached themselves to small rocks. You can eventually find a huge island, as well as smaller underwater islands, being held afloat by huge versions of the same creature.
    • The wall of the escape pod says that the bacteria count in the water is high. One of the first items the player can craft is short-range scanner. After a while, upon scanning oneself, the display on the scanner reads "INFECTED".
    • The first data file on Peepers mentions they have a pointlessly enlarged nasal cavity designed to detect a single, very specific odor which absolutely nothing yet encountered produces. You can also spot Peepers emitting a strange glowing trail, which, if scanned, are coated in some strange substance which inhibits bacterial growth. It's designed to detect Enzyme 42, and is the first hint of the Emperor Leviathan's deliberate alterations to the Peepers to help it save the ecosystem from the Kharaa Bacterium. Those glowing trails are also streams of unstable Enzyme 42, bestowed upon them by the Leviathan and released via the Alien Vents.
  • Fungus Humongous: The Mushroom Forest and Jelly Shroom Caves.
  • Game-Breaking Bug:
    • A particularly nasty persistent bug occurs when you save your game, which causes any partially researched blueprint to lose all progress and force you to start over. It seems to have been fixed with the full release tho.
    • There's still a lot of clipping issues even after the game went gold. The player can often fall through the seabed, even in a vehicle, requiring console commands to warp you away, often at the cost of your vehicle.
  • Gentle Giant: Some of the creatures you encounter will be this, such as the monstrous, loud, but harmless Reefback. You won't know unless you get spotted by them or go up to them, though.
  • Giant Enemy Crab: The ambiguously-scrapped Rock Puncher and the definitely-scrapped Grabcrab.
  • Giant Squid: The Crabsquid, which was implemented in the Machinery Update. Oh, and it can walk on the seafloor and produce EMP blasts.
  • Glowing Flora: Many deep-sea plants (this includes a tree) are just as bioluminescent as the rest of the living things living there. This was probably to exaggerate the stereotypical abyssal theme, since many bioluminescent creatures live in this biome in Real Life.
  • Going Critical: The Aurora’s reactor explodes, releasing lethal radiation in the surrounding area which will kill you without a Radiation Suit.
  • Grappling-Hook Pistol: One of the PRAWN upgrades. Essential if you're taking it anywhere deep.
    • Fun for latching onto a Leviathan and going for a rodeo ride.
  • Greed: Paul Torgal's search for a resource-rich celestial body is what doomed the Degasi and as a consequence the Aurora and the Sunbeam. Justified as mining was his job, and no one could have expected to be shot down by an automated Orbital Defense Platform.
  • Green Hill Zone: The Safe Shallows.
  • Hazmat Suit: The whole of the Radiation Suit, the Radiation Gloves, and the Radiation Helmet. Lack one, and the radiation will harm you.
  • Heal Thyself: Medical packs will heal you completely and instantly. It's unknown if future updates will add tiers to your supplies, so you'll have to be more careful in the beginning when you can't make the strongest ones.
  • Hearing Voices:
    • The Mesmer will do this to you if you get too close.
    PDA: It is your primary directive to swim closer to that beautiful creature... Do not resist... Don't struggle...
    • The PDA entry says the pattern on its fins basically makes you perceive the most trustworthy source to tell you the above message. In the protagonist, that's obviously the PDA. Wonder what the other fish hear/perceive.
    • Your first encounter with the Sea Leviathan is hearing its voice from nowhere. It's later shown that it speaks to you through telepathy.
    What... are... you?
  • Heel–Face Turn: In a meta example, the Cute Fish was the original Crashfish, a fish which hides inside a plant and pops out to charge at you and explode if you get too close. However, everyone agreed it was too cute, and rewrote the Cute Fish's AI as a pet which follows you around and chirps delightedly.
  • Hell Is That Noise:
    • The radio's beeping whenever it picks up a new message. The first few messages you get are distress signals from fellow survivors. As you go to explore, which is needed to continue the story and get more messages, you'll find out they all already have died. From that point on, the beeping becomes a grim reminder because you know it won't lead you to survivors but to their final PDA files often giving a good idea of how their final moments were. Then after a while, the radio starts picking up on messages that aren't from fellow survivors but from Warpers hunting for them. And for you.
    • It's not unusual to hear creatures before seeing them. The Reaper Leviathan's PDA entry ups the discomfort of its roar with the following line: "The deep roar emitted by the reaper at regular intervals is effectively sonar - if you hear it, the reaper can see you."
  • Hoist by His Own Petard: The player can do this to themselves if they breed Crashfish and then set them loose outside their base. Sure, the fish won't attack you because it grew up docile, but it will attack other fish by suicide bombing them right next to the hull of your base, causing a breach, a flood, and a panicked flail as the player runs all over trying to find the hole. Why, no, this isn't inspired by a true story at all...
  • Homing Projectile: Torpedoes will, if a Leviathan is present, immediately home in on them to the exclusion of anything else. Given how immensely dangerous Leviathans are, this is an extremely welcome quirk.
  • Hope Bringer: The protagonist. Almost by accident, they complete the Precursor's work of saving the Sea Leviathan population and stopping the Kharaa epidemic.
  • Hope Spot: Another ship, the Sunbeam, picks up the emergency distress signal from the Aurora and comes to help... only to share the Aurora's fate, being blasted out of the sky by the precursor gun. There are no survivors this time.
  • Hot Blade: One of the upgrades for the Survival Knife equips it with a heating element, causing the edges of the blade to glow red. Mostly this is used to kill and cook edible wildlife in one action, the upgrade actually reduces the damage dealt with the blade in exchange for its new ability.
  • Improvised Weapon: The developers (and, In-Universe, the Alterra company) intentionally made the game lack true weaponry besides Torpedos, but that doesn't stop particularly paranoid or violent players from taking revenge against the sea life.
    • The Propulsion Cannon, originally designed as a short range logistical tool, can be used to grab and toss crates at sea life, or to pick up smaller creatures and slam them against walls for lethal damage. There's also a variation on a PRAWN Suit's onboard storage to give it a sort of ammo magazine.
    • The Repulsion Cannon upgrade for the Propulsion Cannon completely removes the ability to pick things up, going directly to blasts of force. Of course this is intended as a self-defense tool to get away from animals, but it's still quite easy to smash a shark against the sea bed multiple times until it dies.
    • In the same vein, the Drill Arm is primarily an industrial harvesting tool, but three shrieking, grinding blades are remarkably handy for convincing a hungry Reaper Leviathan to seek out easier prey when applied vigorously and mercilessly.
    • Even the default Prawn Suit arms are quite powerful. A few punches to a Stalker will very easily kill it, even when the arms' primary use is to pick up resources without getting out of the suit.
  • In-Universe Game Clock: There's a day-night cycle which not only informs what creatures you'll see, but also how aggressive they'll act; most are bolder at night.
  • In-Vehicle Invulnerability:
    • Played With in the opening cinematic. The player climbs into an escape pod and gets promptly knocked out by a piece of metal smacking them in the face. However they also end up being the only survivor of the Aurora crash.
    • Played straight by all vehicles, which have a separate health meter from the player. While running into things may damage your vehicle, you'll never be knocked unconscious by flying shrapnel like in the opening movie. The Cyclops was once immune to the attacks of creatures, even Reapers (who can destroy your Seamoth in two bites), but it now has a health bar like the others and can be damaged and destroyed if you're not careful.
  • Item Farming: Titanium and quartz in particular, because those are needed for bases and vehicles.
    • The primary function of the Alien Containment, which makes farming food, water and energy a breeze, freeing up time to truly begin your exploration of the ocean.
  • Jet Pack: A vehicle announced for possible inclusion after V1.0.
  • Jump Jet Pack: Built-in feature of the PRAWN suit. There's an upgrade to improve the jump too.
  • Killed Offscreen: At one point, the radio intercepts a piece of inter-Warper communication stating that there are nine Aurora survivors unaccounted for. Soon thereafter, another communique states that there's only one of them left (guess who), implying that the rest are being eliminated while you're doing whatever.
  • Kraken and Leviathan:
    • The PDA uses the term "Leviathan Class" to describe the biggest of the big. Note that this is just a size classification, the 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 run and don't look back.
    • One PDA entry indicates that the tremendous size of the Sea Emperor means they're going to have to recalibrate their size scale.
    • In the 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, giving the descriptor "leviathan" a real workout.
    • A “kraken” type creature is a frequent suggestion on forums and the game's subreddit.
  • Late to the Tragedy:
    • Seconds after the protagonist escapes the Aurora, they are knocked out cold by a panel that has gotten loose. By the time they wake up, all other people who made it off the ship have already perished. And that's to say nothing about what happened on Planet 4546B in the first place.
    • The presence of a meteor in the Dunes and some of the PDA's suggestions imply the Precursors qualify for this trope as well, and releasing the Kharaa only rubbed salt in the wound.
  • Lethal Lava Land: The Inactive Lava Zone and the Active Lava Zone.
  • Lightning Bruiser: Reaper Leviathans, full stop. They can swallow the player whole, can crack a Seamoth in two hits and players are physically incapable of outrunning them.
  • Lily-Pad Platform: Presumed to be the case with the yet-to-be implemented Lilypad Biome.
  • Loading Screen: There's only one, when you're starting a new game or loading a saved game.
  • Loads and Loads of Loading: However, unless you have a fast computer and fast hard drive, you will be staring at that initial loading screen for several minutes.
  • Meaningful Name: Invoked, since your PDA is generating names for creatures as you encounter them, so almost all of them have names directly tied to their distinctive traits. In fact, the Reginald actually sticks out as being the only fauna that doesn't have such a name.
  • Mega Corp.: The 37 "trans-gov" corporations that control the galaxy. Two matter in the game: The Alterra Corporation that owns the Aurora and makes just about everything seen, and the Mongolian Empire that owns the Degasi. note 
  • Minimalist Cast: The player character is the sole human on the planet, and the other alien species there seem to be fairly normal animals in terms of intelligence.note  You can eventually find some old notes from previous crash survivors, but the state of their bases should be more than enough to tell you that they're long gone.
  • Mini-Mecha: The Pressure Re-Active Waterproof Nanosuit A.K.A. the PRAWN Suit, previously the Exosuit. It shares some upgrades with the Seamoth such as Pressure and Impact Compensation, but also has special arm variants that can be interchanged separately from the regular upgrades.
  • Mix-and-Match Critter: Some of the creatures have elements of two or more creatures. The Crabsquid is an octopus with Japanese Spider Crab legs and claws. The Sea Dragon Leviathan is a crocodilian with squid tentacles for its lower half, and the Emperor Leviathan is similar but with an insectoid/crustacean head.
  • Mood Whiplash: Appears in the soundtrack. Most of the songs are appropriately mellow for a game that predominantly takes place underwater. But the aptly named Abandon Ship, which plays when the Cyclops suffers critical damage, is ironically upbeat.
  • More Predators Than Prey: 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.
  • More Teeth than the Osmond Family: Stalkers, but it's cool because you need the teeth and they've got an endless supply of them. Sand Sharks have several rows of teeth going down into their throats.
  • Nature Is Not Nice:
    • 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  or running out of oxygen while looking for resources.
  • No Biochemical Barriers: 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 somewhat necessary for the game to be enjoyable to play,note  though it would be nice to imagine you at least give the Reapers indigestion after they eat you for the hundredth time.
  • No Body Left Behind: Despite having 157 people on board, not a single shred of a body can be found in the game. No blood splatters, no bones, no clothing scraps, no nothing. Meanwhile, several wrecks contain potted plants that got through the crash in one piece. Justified as the Warpers kidnapped and/or killed all of the survivors. And if it's the latter, their scythe-like arms are definitely sharp enough to avoid leaving behind tangible amounts of remains.
  • Not the Intended Use: 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 map system of its own.
  • Ocean Punk: It's a mostly underwater survival game.
  • Oh, Crap!: The traditional reaction to a player hearing any of the distinctive roars that signal an imminent encounter with any of the three aggressive Leviathan species.
    • Also the likely reaction of a player being in position to witness the demise of the Sunbeam for the first time. It's proposed landing site is right outside the Quarantine Enforcement Platform, which resembles a curious alien tower when idle. Right before the hapless ship enters the atmosphere, the Platform begins to emit an alarm and starts changing shape. Before too long, the player will realize it's beginning to resemble a colossal gun turret. One that is now tracking the approaching Sunbeam...
  • One-Gender Race: The PDA mentions that all life on Planet 4546B is only one sex, they do not reproduce asexually though as each individual can both carry and fertilize eggs.
  • One-Hit Kill:
    • The Reaper Leviathan, if you are not inside a vehicle. And even then you only can take a few chomps before the can opens to reveal your fleshy form. note 
    • The Sea Dragon Leviathan can eat you alive. It is exactly as terrifying as it sounds.
  • Our Dragons Are Different: The Sea Dragon. It has a reasonable upper body of an aquatic dragon, plus squid legs.
  • Our Fairies Are Different: Rockgrubs are basically aquatic fireflies.
  • Oxygenated Underwater Bubbles: Either naturally when produced by Purple Brain Coral or manmade when produced by a pipe system.
  • Oxygen Meter: Unaided, you can hold your breath for 45 seconds. You can get tanks which 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.
  • Palette Swap: There are currently five creatures that are a texture swap of other creatures: Crimson Rays to Ghostrays, Blighters to Biters, Spinefishes to Hoopfishes, Lava Boomerangs to Boomerangs, and Lava Eyeyes to Eyeyes. The game also includes a few models that are not texture swaps but still very close in appearance to other models, such as Jellyrays and Ghostrays and Blood Crawlers and Cave Crawlers. Creatures part of the design repeats are explained to be genetically related.
  • Patchwork Map: Complete with Law of Cartographical Elegance.
  • Percussive Maintenance: When trying to free themselves from the chair in the beginning, the protagonist presses the button several times to no avail. So he slams his fist down hard on the panel, which naturally works.
  • Piranha Problem: Biters, which hunt in small schools and chase you from further away if your health is low.
  • Portal Network:
    • The reason why the Aurora was near 4546B was because it had visited the system to construct a phasegate here (though given no-one mentions going into cryosleep or anything of the like, it seems more "conventional" FTL travel is also a thing).
    • The precursors have created an entire network of portals on the planet's surface, connecting both islands as well as various facilities. By the time you arrive, they are shut down to stop the Kharaa from spreading - although they can be restarted from the Primary Containment Facility. The PDA describes them as miniature phasegates.
  • Powered Armor: The reinforced diving suit and the PRAWN qualify - the latter especially, as in addition to making you very tough to kill, it provides an infinite supply of oxygen, increases your speed. Also, if you mount the grappling hook, it allows you to move around much faster than swimming with just fins. The PDA even warns you against going on a power trip the first time you use it.
  • Precision F-Strike:
    • In a log file on the Habitat Update's webpage.
    Controller: (responding to the Aurora’s survival PDAs running version 1.0) Bring me every star chart, tech geek and concentration enhancer in the building...
    Analyst: Yes Ma’am!
    Controller: ...and god DAMN it you build me an update package, and you find me a way to flash them Version 1.1!
    • And later this on the Seamoth Update's webpage.
    Controller: Ship [the survivors] the Defense System and the Vortex Torpedoes.
    Analyst: But ma'am, weapon designs violate directive 7!
    Controller: Directive 7 is there to eliminate the risk of survivors turning on one another. If they're going fin-to-fin with alien krakens then they have bigger fish to fry. I want them prepared, and damn the directives!
  • Primal Fear: One of the more obvious fears that the player can experience is the depths of the ocean floor. It's impossible to tell what may be swimming beneath you, especially if you're out during the night. You have no way of knowing what could be a threat unless you choose to confront the creature. Not to mention that you're on an alien planet, giving you more reason to be afraid.
  • Pure Energy: Any power source built outside (and power transmitters) transmit the energy to the nearest base not by cables, but by a beam of sorts.
  • Recoil Boost: In a non-weaponized example, spraying the fire extinguisher underwater will cause you to move backwards. Slowly, yes, but it can be a fun distraction. Above water (i.e. in your base or the Aurora), there's naturally no recoil, as your feet are firmly planted.
  • Regenerating Health: Your health recovers slowly but surely.
  • Respawning Enemies: The creatures of Planet 4546B eventually respawn. Yes, this includes Leviathans.
  • Retractable Weapon: How the Quarantine Enforcement Platform innocuously disguises an energy weapon capable of felling a flying city like the Aurora in a single shot.
  • Ribcage Ridge: The Bones Field in the Lost River area contains a large, dragon-like skeleton. A couple of smaller versions of the same skull and bones have been added as well, and the skeletons of Reaper Leviathans and Sea Dragon Leviathans will be added in the future. It's basically the undersea equivalent of an Elephant Grave Yard, and there is Truth in Television, as underwater cavern systems can trap animals that go into them.
  • Salt Solution: Salt is needed to conserve dead fish or they'll go bad very quickly. It is also an ingredient to create bleach for disinfecting water and making health kits, and it's needed for a number of vehicle upgrades.
  • Sea Monster: Applies to a lot of creatures in the game simply for what they are, but the trope takes full effect in the Void, the area of nothingness that surrounds the playfield. To avoid the Invisible Wall or Wrap Around, Subnautica hosts scores of the worst of its fauna the farther into the Void the player gets. It starts with Crabsquids, then kicks up to Reapers, and ends in Sea Dragons.
    • As of the full release, this is not the case anymore. Instead, venturing out into the void, now known as the Crater's Edge, now spawns Ghost Leviathans. It's as terrifying as it sounds too: You hear an echoing roar in the distance, and then from the depths this transparent writhing phantasm charges at you. It's unrelenting, will always home in on you, can deal heavy damage to a Seamoth in one blow... and it can move faster than a Reaper Leviathan. Be prepared for a challenge if you hope to survive an encounter with it.
    • It's not uncommon to have three or more bearing down on you, and they'll quickly turn a Cyclops into scrap. Launching creature decoys and using the Cyclops's shield is a temporary fix.
  • Send in the Search Team: What the Aurora is to the Degasi and the Sunbeam to the Aurora.
  • Scenery Porn: The game's main selling point - the designers worked very meticulously to invoke this trope, and the result truly must be seen to be believed.
  • Scripted Event: Radio messages and PDA log files. The explosion of the Aurora and the Sunbeam being shot out of the sky both qualify as a Video Game Setpiece.
  • Shared Universe: With Natural Selection 2, also made by Unknown Worlds. Originally the name of the Alterra corporation on the Knife's blade was considered merely an easter egg, until a log file coded with a Caesar cipher and ASCII on the Habitat Update’s promotional webpage mentions “the Kharaa conflict," and as the game's wiki notes, the Kharaa are, in fact, connected with the Kharaa Bacterium in some fashion. note 
  • Shock and Awe:
    • The Ampeel uses this, similar to a real-life electric eel.
    • The Seamoth's Electrical Defense upgrade, which is more realistic.
  • Shown Their Work: 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 two batteries.
  • Single-Biome Planet: Thoroughly averted; the underwater world has rich and diverse areas, varying not only by location but also by depth.
    • In the game's ending the planet is also shown to have a number of large islands and polar ice caps.
  • Solid Gold Poop: What Sea Treaders drop. It's only useful as biofuel right now but is expected to be crucial to farming later in development.
  • Something Completely Different: The entire game takes place in the ocean, except for your life pod, the crashed Aurora, a floating island, a true island, and a Lilypad Biome yet to be implemented.
  • Sound-Coded for Your Convenience: All the wildlife is quite noisy, and makes unique sounds to boot. Learning which creatures make which sounds lets you know when it's just a big Reefback saying hi and when you're about to be eaten alive.
  • Space Isolation Horror: The game leaves you stranded on an ocean planet full of large, terrifying sea monsters who want to eat you.
  • Spike Shooter: The Tiger Plant, which you can also grow yourself.note 
  • Sprint Shoes: The basic underwater variant are a pair silicon flippers, which slightly increase the player character's baseline swimming speed, which can be upgraded into Ultra Glide Fins. The straighter variant though is the Seaglide, which is a fancy DPV, or a propeller with handles. It comes with a local topography map and flashlight. It's also able to be recharged indefinitely with Swim Charge Fins (which may or may not change in future updates.
  • Standard Status Effects: Played with. When in contact with Drooping Stingers or the Gas Pods from Gasopods, the health bar dwindles rapidly due to poisoning. Escaping the contact will return all the health lost.
  • Stat Death: Running out of oxygen won't do anything to your health bar, but you'll die anyway if you don't reach an oxygen-rich environment soon.
    • Similarly, if you actually run out of food or water, you will die from malnutrition or dehydration. Bleeders will drain your food level while attached to you, so it's entirely possible for you to starve to death from getting bitten.
  • Sub Story: The Cyclops in particular. Silent Running Mode is coming up.
  • Super-Persistent Predator: Largely averted. 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 are the Reaper Leviathans, which seem to be apex predators. If one spots you, run. Run and don't look back. Or, seeing as it can outrun your Seamoth and also tear it to shreds in seconds, 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.
    • They also won't be distracted for long by Creature Decoys which can be hand dropped or launched by the Cyclops. Hell, even being scooped up in a PRAWN suit and using the drill arm(s) to fight back won't make a Reaper let go of you, to say nothing of the other two mean beasties.
    • The single most reliable way to evade them is judicious application of a Stasis rifle or a Vortex torpedo, which are capable of paralyzing a Leviathan for several precious seconds while you try to flee.
  • Swallowed Whole: What happens after the aforementioned Reaper Leviathan catches you. Also one of the ways the Sea Dragon Leviathan can seal your doom, if it doesn't roast you with its fire breath.
  • The Symbiote: The Crashfish and the Crashfish Plant as well as the Crabsnake and the Jellyshroom.
  • Take Your Time: The game very heavily implies that you will die after about five weeks, thanks to exposure to the Kharaa bacterium and that symptoms should start appearing around two weeks in. Instead, the disease's progression is entirely event-based, and the player will never fatally succumb to it. Slightly justified, thanks to the presence of Peepers spreading diluted Enzyme 42, which inhibits the bacterium's growth and progression. For the same reason the Kharaa hasn't wiped out the entire biosphere, it's possible Ryley is kept alive via indirect exposure.
  • Ten-Second Flashlight: Downplayed with the hand flashlight, which lasts a fairly long time on a full battery, but not nearly as long as one would expect with all the other high-tech gizmos those batteries can run. Vehicle lights come in two flavors: the Seamoth and Seaglide have a small drain when the lights are on, while the PRAWN and Cyclops provide light for free.
  • This Is a Drill: An exceedingly useful modification for the PRAWN is a huge drill arm; specifically, a grinder-style drill, intended to pulverize mineral deposits for harvesting rather than tunnel through the ground.
  • Threatening Shark: The Stalkers (during development also known as Snout Sharks), Bone Sharks, and Sand Sharks.
  • Unbroken First-Person Perspective: The closest to a break is when you control one of the Camera Drones and can see yourself at the console if you have a well-placed window. But even then what you see with the camera is what the character sees on the console.
  • Unexpectedly Realistic Gameplay: It's not obvious from the start that oxygen tanks actually store oxygen rather than merely increasing your cap. Plus they are active even if you don't equip them into the slot, so if you have several of those in your inventory, you will have a much larger oxygen reserve.
  • Under the Sea: Almost the entire game takes place in the ocean, with a couple of islands and the non-submerged half of the Aurora being the only exceptions.
  • Underwater Base: You can make these using the Habitat Builder and raw materials such as titanium and glass.
  • Unstable Equilibrium: The beginning of the game is almost exclusively about basic survival: getting food and water to stay alive long enough to get equipment to survive the planet's dangers. Obtaining the means to farm your food is a huge step in freeing up time to spend on exploration, but certainly isn't the only boost forward.
  • Villain Teleportation: Well, Threatening Force Teleportation, anyway. Warpers are cyborgs with built-in teleportation hardware. They can come and go as they please. A possible future update will give the protagonist teleportation too, but by means of external teleportation platforms that need to be placed in advance.
    • Warpers actually have weaponized their teleporters, attacking primarily by warping in hostile fauna directly on top of you which is always appropriate to the biome you're in. It even works in reverse, as they can warp you out of a vehicle you thought you were safe in.
    • The Precursors already have a network, though that needs to be activated from a late-game story-required location anyway.
  • Volcano Lair: The Lava Castle, a massive castle-like rock formation located deep within the Inactive Lava Zone. It's home to the Precursors, along with the Active Lava Zone directly below it. All of their power comes from the Lava Castle, and is budgeted into various operations.
  • Walk, Don't Swim: As far as creatures go, Cave Crawlers, Blood Crawlers, and Sea Treaders. The player is capable of this too when controlling the PRAWN suit.
  • We Hardly Knew Ye: Every single human and the precursors qualify, but Captain Avery Quinn takes the cake.
  • Well-Intentioned Extremist: The Precursors. They were the ones responsible for shooting down the Aurora and Degasi, and later the Sunbeam that lands to try and rescue you in front of your own eyes. However, there's a reason they're doing all of this. A bacterial epidemic ravages the planet, which has infected enough creatures to become the norm. The Precursors want to cleanse the planet of the bacterium... by killing all those with it. In desperation, they built the surface-to-orbit oversized cannon, euphemistically called the Quarantine Enforcement Platform, and wound up killing a bunch of Sea Emperors - note the plural; 314 to be exact - trying to find a cure. They also created the Warpers.
  • The Worf Effect: Reaper Leviathans are highly dangerous early in the game. In and around The Lava Zones are Reaper skeletons that the Sea Dragon left behind after eating them.
  • Worthless Yellow Rocks: Played with. Gold is the one resource that plays a special sound every time you pick a piece up. It is also the only resource found in three of the five available harvest nodes (Sandstone, Basalt and Shale). While there are some uses for gold, its first two harvest node colleagues, silver and lithium, are more sought after as they're used in recipes more crucial to survival. Explanation  Averted in the Silent Running update, which changed the recipe for the Computer Chip to accept Gold instead of Silver.
  • Yank the Dog's Chain: After everything the survivor goes through, from scavenging for food and water, to fending off giant predators, to curing a disease that has plagued the planet for over a thousand years, he finally builds a rocket and escapes, only for 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 brought Precursor 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.
http://tvtropes.org/pmwiki/pmwiki.php/VideoGame/Subnautica