Video Game / Aliens: Dark Descent

Aliens: Dark Descent is a 2023 squad-based Real-Time Strategy game in the Alien franchise, developed by Tindalos Interactive (who had previously made Warhammer 40,000 Battlefleet Gothic: Armada and its sequel) in collaboration with Disney's 20th Century Games and published by Focus Entertainment for Windows and all major contemporary consoles.

Players control a single squad of colonial marines and navigate them through various bases and hives to accomplish various mission objectives. Levels are designed to be visited multiple times instead of accomplishing all mission objectives in one go, as the marines in your squad are susceptible to fatigue, stress, and injury. Changes made to levels by the player are also permanent, for example if a door is welded shut it will remain so until opened again by the player for all future visits or broken open by Xenomorphs. The game takes inspiration from Darkest Dungeon in the development of the marines in the player's squad, as they come with various character defects and can develop maladies if their morale is allowed to remain low, but can also be leveled up with experience.

Set 20 years after the events of Alien³, the game takes place on the colony moon of Lethe, in orbit around a gas giant planet and home to a Weyland-Yutani mining and transport hub base. When a xenomorph infestation breaks out on the moon Wey-Yu's deputy administrator Maeko Hayes activates the company's Cerberus Protocol to prevent the infestation from spreading, causing the moon's orbital defenses to shoot down all ships in orbit including the United States Colonial Marines ship Otago. Now Hayes and the crew of the Otago, led by Sergeant Harper, must gather resources to repair the crashed ship and escape the Alien-infested moon.

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This game contains examples of:

• Admiring the Abomination: Dr. Becker quickly becomes fascinated with the Xenomorphs, requesting genetic samples from them in order to learn more about them and their possible weaknesses. He would also love to get an actual Xenomorph for study, but both Harper and Hayes refuse on the grounds that it's too dangerous. Becker finally gets his wish when a Darwin Era Guardian stows aboard the Otago and allows himself to be held in laboratory containment. Through examining the Guardian and the Chestburster inside him, Becker is able to learn much about the Xenomorphs and Marlow's research, recording the resulting data in the Otago's computers.
• Advancing Boss of Doom: The massive ancient "Space Jockey" xenomorph encountered at the very end of the game is completely unkillable, so the game's finale consists of Hayes and Cassandra running away from it as it chases them through the ancient city.
• All Your Base Are Belong to Us: Late in the game, Pryce has Becker sabotage the Otago's defenses so that a Wey-Yu commando team can seize the ship while most of the Marines are away on a mission. It's only Hayes' intervention that manages to thwart the plot.
• Alien Autopsy: The xenos don't always leave remains behind, but the few remains that they do leave that are semi-intact can be collected by marines in the field to analyze back aboard the ship. The substances extracted from these "xeno samples" can be expended to activate buffs for the duration of a given deployment, such as a coating on the marines' armor that makes it more resistant to acid blood or a pheromonal spray that makes them harder for the aliens to detect.
• Always Close: Once the final mission begins, the planetary bombardment by the Cerberus satellites is always treated as imminent regardless of how many in-game days have passed.
• Ambiguous Robots: Director Pryce of all people. Hayes speculates that they may be actually synthetic as an explanation for their behavior throughout the game but it is never proven one way or the other.
• An Arm and a Leg: Both your marines and the xenomorphs can be dismembered in combat. Xenomorphs usually lose a leg, which slows them down significantly but makes them no less deadly if they get into close combat. Marines can lose any of their limbs but can receive Artificial Limbs as replacements in the medbay, provided you get them stabilized and evacuated quickly enough.
• And Now for Someone Completely Different: While Hayes is the player character, most of the way the player controls her is as a mission commander directing teams of marines via radio. However, there are several missions where the player will control her directly instead of the usual squad command, such as the tutorial, when a xeno gets loose aboard the Otago, and the ancient alien city deep beneath the Olduvai trimonite mine.
• Anti-Frustration Features: About 1/4th of the way through the game, the Otago is attacked by a swarm of Xenomorphs, preventing you from going on other missions and forcing you into a base defense mission. Immediately before this happens, you receive 4 new marine recruits, so if all your marines are wounded or in therapy/training, you'll still have 4 marines to do the mission with.
• Anti-Vehicle: Colonial Marines can be equipped with rocket-propelled-grenade launchers for precisely the purpose of allowing a squad of infantry to threaten light-armored vehicles. There aren't really any enemy light-armored vehicles for them to threaten in the game, but it turns out rocket-delivered shaped explosive charges designed to puncture layers of defensive alloy are also pretty good at puncturing the carapaces of "Category 2" xenomorphs.
• Anyone Can Die: By the end of the game most of the main and supporting cast have been killed, including Sergeant Harper who exhausts himself in a Heroic Sacrifice using his psychic abilities to save his daughter, with the only surviving named characters being Hayes, Cassandra, and the dropship pilot, chief engineer, and psychiatrist.
• Artificial Limbs: Marines that lost an arm or a leg in combat may return to active duty with a prosthetic replacement in place. Getting two of these on a single marine unlocks an achievement.
• Artistic License – Physics: The game states in the item descriptions that its plasma weapons have an output in the low milliwatt range. In other words, even the APCs twin-linked Plasma Cannon hits with about 0.1% of the power of a lit candle. Given how useless this weapon is, this value might just be accurate. The plasma rifle available to level 10+ marines is far more powerful than that, though.
• Awesome Personnel Carrier:
  • The Otago is equipped with a functional Armored Recon Carrier, a smaller cousin to the classic M557. It's large enough to carry a half-section of marines, with light angled armor and better suspension for off-roading. It's less well armed than the M557, sporting only the M557's front turret weaponry in a mounted top turret, but it still serves as an effective mobile base of fire support for marines in the field.
  • The crew of the Otago eventually finds an old classic M557 Armored Personnel Carrier, leftover from when the Colonial Marines suppressed a rebellion on Lethe a few decades ago. It's equipped with the same twin-linked rotor cannons as the ARC in a front turret, but it also has a pair of twin-linked plasma cannons in a top turret, increasing its firepower drastically. More importantly, its larger interior volume can support a larger number of marines, permanently increasing the deployable squad's size.
• Backtracking: Unlike other tactics games that take inspiration from either X Com Enemy Unknown or Darkest Dungeon, there is not a randomly-generated level layout in play and locations are revisitable; allowing a measure of persistence especially as corpses or loot pile up as the playthrough progresses. This is actually recommended as one of the ways to bring the continuous pressure and endlessly intensifying onslaughts from the Xenomorphs in a singular location down is to move on and return at a later time. However, this also can be very costly to play this safe in the latter half of the game where time is of the essence and leaving a location and revisiting later will spend crucial moments before the Cerberus Protocol enters Phase Two, which forces the difficult decision of either leaving an area behind and coming back later at the cost of time or sticking it out and accomplishing every objective in one sitting despite the increasing difficulty.
• Bait-and-Switch: A portion of the final level requires your marines to run through a cluster of abnormally large eggs. But despite the setup and some trolling by an android, you never have to face giant facehuggers, because they would be too big to infest a human.
• Beauty Is Never Tarnished: Both averted and played straight. Maeko gets through the game without a scratch, somewhat justified in that she rarely takes the field herself, but Cassandra is shaved bald, has numerous scars, and is clearly emaciated from her imprisonment.
• Body Horror: Aside from the usual Xenomorph lifecycle, there's the Guardians, cultists who have been implanted with a device known as Embryostasis which replaced most of their torso, neck and mouth, and holds the Chestburster inside them in stasis, slowing its gestation process while allowing them to walk among the Aliens without being attacked by them. The end result makes the Guardian look at home in Scorn with how severely transformed they are to accommodate the embryo.
• Boring, but Practical: As opposed to more flashy equipment and abilities, the placeable Motion Trackers simply keep you more informed of enemy movement, but they also have the ability to overheat themselves to draw attention and self-destruct. Since players have unlimited amounts to deploy if they wait for their CP to regenerate, they have essentially unlimited bait to draw enemies away or into trip mines or the APC’s cannons, and any kill by those means neither alerts the Hive nor raises the threat level.
• Boss in Mook's Clothing: Crushers and Praetorians are the toughest individual xenomorph units other than a Queen, and a single one can serve as a major obstacle for your squad.
• Broken Pedestal: Hayes in regards to Director Pryce. Early on she clearly aspired to be more like the high ranked executive, being quick to seek her input and defending her actions to the marines. This attitude wanes as the full extend of Weyland-Yutani and by extension Pryce's ruthlessness becomes clear.
• Canon Immigrant: The game's story incorporates a number of themes and concepts from the Aliens Expanded Universe comics and novels from the 90s, such as the Alien hive having a psychic presence, and human cults that worship the Aliens due to going insane from exposure to said psychic presence. The dead ancient aliens in the alien city at the very end of the game also appear to be original "Pilots"/"Space Jockeys" from the 90's comics rather than Prometheus "Engineers".
• Chronic Backstabbing Disorder: Director Pryce has no qualms about screwing over her partners and underlings if it advances Weyland-Yutani's interests. First, she tried to steal Marlow's research, then sends Stern and his team on a suicide mission to recover it. She later betrays her temporary alliance with the Otago by attempting to seize the ship for herself.
• Closest Thing We Got: While searching for survivors in the first mission to Dead Hills, the marines come across a veterinarian who mostly treats cattle, and only occasionally stitches up a person. The marines want to bring her aboard the Otago because they're desperate for qualified medical technicians and even a veterinarian is better than no one. Said veterinarian is abducted by the aliens in a Scripted Event during her rescue. If the marines can track down the local alien nesting hive, they can rescue her again before a Face Hugger can get to her.
• Company Town: Lethe, originally an independent frontier colony, was forcefully annexed by Weyland-Yutani and other megacorps when trimonium was discovered on the moon, which among other bad things resulted in a worker rebellion that was brutally quelled by the USCM and corporate security forces. When the trimonium deposits ran dry, only Wey-Yu remained to lord over a dwindling population of ex-miners and cattle farmers that were too poor to afford passage off-world.
• Crapsack World: With the entire Aliens setting being a Crapsack Universe through and through, this was to be expected. The moon of Lethe is an inhospitable rock at the ass-end of nowhere that humans couldn't even survive on without massive atmosphere processors, which are in the process of breaking down after decades of neglected maintenance. Its main economic asset - its trimonium mines - ran dry long ago, leading all the corporations involved except for Wey-Yu to pull out, and we all know how Wey-Yu tends to treat its employees. And then xenomorphs showed up. By the time the plot kicks off, most of Lethe's remaining population is already dead or dying, and it only goes downhill from there.
• Crazy-Prepared: Weyland-Yutani, who are shown in-game to be notorious for "economizing" their expenses, went through the trouble and cost to put an entire network of satellites armed with anti-ship and nuclear warhead missiles, just to enforce a state of extreme quarantine on Lethe in case something went wrong. It's fortunate they had the foresight to do so to contain the xenomorph threat, but it also hints that the company is not as ignorant or innocent of the experiments Marlow was performing as they pretended to be.
• Cruel Mercy: After confronting Director Pryce in person for the first and last time, Hayes refuses to take Pryce aboard the Otago and simply leaves her alone in her private office. Outside, hundreds of Xenomorph drones are climbing the walls and are about to reach the office, leaving Pryce's survival very unlikely.
• Cult: One of the main antagonist groups is a cult known as the Darwin Era led by a rogue Wey-Yu scientist who have developed a way to use cybernetics to arrest the chestburster incubation process, allowing them to walk freely among the xenomorphs who identify them as members of the hive. However their cybernetics only delay the inevitable, and the cult members do eventually pop just like anyone else. Being insane fanatics, they seem aware of this and have embraced it.
• Escape from the Crazy Place: The main goal of the game is to repair the Colonial Marines' ship so they can escape the infested moon.
• Escort Mission: Downplayed in a couple of different ways:
  • Various civilians can be located and rescued during missions. When rescued they will follow the squad (or need to be carried in the case of unconscious ones) and need to be guided back to the squad's transport vehicle before they can be extracted. They're particularly vulnerable during this time, not having the marine's armor or weapons, and can be easily killed if the squad gets too deep into conflict. However, rescuing them is the game's primary method of recruiting medical specialists, engineers, and fresh trainable marine candidates to put through an impromptu boot camp.
  • Occasionally one of the marines will need to board a Power Loader to move something heavy or force a large door or some other task necessary to make progress. Direct control over this marine is temporarily lost as they execute their duty inside the powered frame. The commotion inevitably attracts enemies, and the rest of the squad will need to defend their otherwise occupied member while they work. Fortunately, the Power Loader itself can take some punishment, but will stop and need to be repaired by expending tools if damaged enough to be disabled and that takes time and resources the squad can rarely afford while under attack.
• Giant Mook: Subverted. In the final level, there is an entire field of giant-sized alien eggs. One of the Marlos encourages the heroes to walk through the eggs to reach him, reassuring them that they're perfectly safe since the eggs aren't meant for someone with their proportions. He then asks them to hurry, claiming the eggs are opening, when they're halfway through, despite the eggs remaining firmly shut.
• Go Back to the Source:
  • Maeko activates the Cerberus Protocol in the opening tutorial mission, and must send a team of marines to return there to try and prevent the second stage of the Cerberus Protocol from going active. They arrive after the abort window had already passed.
  • The crew quickly discover that alien eggs are being put in shipping crates dispatched via rail, which means they can trace to where they're coming from: the Ulduvai trimonite mine, beneath which lies a vast city of Precursors. The crew visits it once while following that lead, and then later when informed about the Underground City.
• Good Costume Switch: Zig-zagged. For most of the game, Deputy Administrator Maeko Hayes wears her Weyland-Yutani executive suit. During the game's final mission in the ancient underground city underneath Olduvai, Hayes appears wearing a USCM uniform, an indication of her fully turning her back on her callous former employers.
• Grenade Launcher: A component^note integrated in older models and optional but still popular in newer models of the pulse rifles that every marine is issued. They do moderate damage but have a respectable blast radius, being used to hit targets behind cover or to blast apart a cluster of eggs in one shot^note Hitting all nearby eggs at once is essential to destroying them without alerting the hive. It's useful enough that it's worth having at least one marine in the squad carry a basic pulse rifle even when more advanced alternative weapons are available just for the utility of the grenades.
• Heel–Face Turn: Captain Stern, the commander of the Weyland-Yutani commandos on Lethe, joins the Otago's crew after a mission to rescue Cassandra fails horribly partly due to Director Pryce being unwilling to give more information than absolutely necessary, thanks to company policy. It also helps that Stern himself is a former Marine, having served six tours of duty as part of the USCM, including the infamous Tientsin Campaign. Later, Stern shows no sympathy to the Wey-Yu commandos who remain loyal to Pryce and the company, since they would commit atrocities in the company's name without flinching.
• Heroic Sacrifice:
  • Stern keeps firing his pulse rifle at a Xenomorph Titan at close range to distract it, yelling at Hayes and Cassandra to get running while he buys them time with his life.
  • Harper burns out his own mind using his psychic powers to freeze that same Xenomorph Titan to give Hayes and Cassandra the time they need to escape.
• Hold the Line: Alerting the Aliens too many time will trigger an Onslaught in which the Hive will send a horde of Aliens to attack the squad. Once triggered, players will have half a minute to prepare for the attack. Once it is over, the level difficulty will increase. Certain missions will also trigger a similar phase.
• I Did What I Had to Do: Hayes' justification for activating the Cerberus Protocol, since otherwise the Xenomorph infestation risked spreading beyond Lethe. While this is largely acknowledged as the correct decision, that still doesn't make her feel any better at the large number of innocents who were killed as a result of it.
• It's the Only Way to Be Sure: Fitting, being part of the trope-namer's franchise, the isolation protocol of the planet involves nuking the planet from orbit.
• Kill It with Fire: Puddles of pearlescent oil are sometimes found on the ground and can be ignited with explosives, to say nothing of the use of the incinerator unit wielded by the marines themselves. This rarely does much damage directly but does apply a temporary damage over time effect that can chip away at crowds. Additionally enemies are loath to walk into the sheet of flames laid down making it an effective way to seal off a corridor, or involve that damage over time by forcing them to do so, or otherwise channel the enemy into a kill-zone. Also works great for frying large numbers of stationary eggs!
• Limit Break: The "Retribution" mechanic. As marines take damage or accumulate stress, the Retribution Gauge builds up. When activated, the marines regenerate a little health and rapidly regenerate command points. As this only builds when the marines are taking damage and getting stressed out, this functions as a bit of a Comeback Mechanic.
• Mad Scientist: Marlow, former Weyland-Yutani xenobiologist, founder/leader of the Darwin Era cult and the Big Bad of the game. During his work for Wey-Yu on Lethe, Marlow made two important discoveries: the ruins of a city built by a race of Precursors underneath the trimonite mine of Olduvai and a father/daughter pair (the Harpers) with psychic abilities uniquely tuned to Xenomorphs. His fascination soon turning into an obsession, Marlow eventually resigned from Wey-Yu, kidnapped the Harper daughter, and retreated into the ruined city to conduct his experiments alone. As his insanity grew, Marlow's distrust of others also grew to the point that he believed that he could only trust himself, which led him to construct countless synthoids in his own image. The psychic emanations from Cassandra and the dormant ancient Xenomorphs in the ruined city gradually drove Marlow and others (usually workers at Olduvai) over the edge until they embraced the idea that Xenomorphs are a truly superior species, which led to the founding of the Darwin Era cult. Eventually, Marlow himself was killed when he was infested with a Chestburster, but his synthoids continued his work.
• Mêlée à Trois: Wey-Yu commandoes and xenomorphs will attack each other as well as the player's squad, and you can lure the two groups to each other to get them to fight so you can take out the weakened victors. Averted with the cult members, whom the xenomorphs identify as part of their hive.
• Mercy Kill: The marines administer one of these to a colonist in Dead Hills after tracking them down, only to find a facehugger already attached to them, apparently having pounced on them while they were on their bunk. After making some futile attempts to remove it, they fire a shot from a sidearm through the facehugger and into its victim's head.
• The Mole:
  • In the mission "Atmospheric Nightmare", there are three civilians to rescue, each of whom is found in questionable circumstances that leave serious doubts about their stories or reliability. It's up the the player's discretion whether to ignore any of them, rescue any of them, or kill any of them. Two are genuine when they assert their situation is Not What It Looks Like, but one of them is a member of the Darwin Era and if let aboard will shortly thereafter take the opportunity to sabotage the Otago.
  • Dr. Becker, the Weyland-Yutani xenobiologist assigned to the Otago. To pay off his own massive debt to the company, Becker eventually betrays the crew of the Otago on Director Pryce's orders with the goal of acquiring the Otago for Pryce's personal use. To do this, Becker releases an imprisoned Xenomorph drone and deactivates the Otago's comms and defenses, enabling a squad of Wey-Yu commandos to dock within. When Hayes foils the takeover and Becker is about to shoot Hayes in retaliation, the freed Xenomorph kills the doctor from behind, much to Hayes' amusement.
• Morale Mechanic: Marines have a stress mechanic representing how badly the carnage and horror they witness is affecting them. Fight enemies, taking injuries, and watching comrades get injured/killed all causes this to rise, and if it hits one hundred percent, they'll start developing traumas that impair them in missions. Stress can be reduced by having marines rest (either between missions at the Otago or in Havens created by welding all doors to a room shut in-mission), while Trauma is managed by using the Psychiatric Care Unit in the Otago's medbay. Treatment for trauma takes days, encouraging you to manage stress carefully.
• Moral Sociopathy: Director Pryce, the executive in charge of Weyland-Yutani operations on Lethe, isn't your typical Corrupt Corporate Executive. She truly believed in her company's goal of creating a better tomorrow, considering any price to make that happen acceptable and believing that Wey-Yu interest and general public interest are one and the same. Pryce considered Marlow's obsession with Cassandra insane but was happy to acquire his research for Wey-Yu's benefit. Unfortunately, Pryce put the company's selfish needs above everyone and everything else, including herself. In the end, Hayes accuses Pryce of being nothing but an obedient synthoid, which Pryce vehemently denies. Interestingly enough, it is never actually made clear whether Pryce is or is not a synthoid- only that she honestly believed that she was not.
• Mythology Gag: Characters frequently use lines from the original films, particularly Aliens.
• Nice to the Waiter: Hayes even treats the Working Joes with respect, treating them like any other employee and even trying to save their lives once the outbreak starts. Unfortunately, while the Wey-Yu Working Joes seem to be significantly more intelligent than the Seegson ones from Alien: Isolation,^note The Codex explains that WY bought up the old Working Joes and upgraded their local Master Computer with one of their own, updating their intelligence in a cost-effective manner. they still suffer from Literal Genie robot logic, and try to "contain" Hayes once the Cerberus Protocols are activated.
• Notice This: In a more interactive example than is typical, players can make the squad sweep their flashlights around in player-directed orientations and anything interactable in line of sight that the flashlight catches will be highlighted. The game's main collectible, the datapads, are also quite visible thanks to their brightly glowing screens.
• Not Me This Time: The Xenomorph infestation on Lethe was not started by Weyland-Yutani, but by the Darwin Era cult, which believes the Xenomorphs to be a far superior species to humans and the next stage of evolution itself. Despite this, Director Pryce did almost nothing to stop the cult despite knowing about Marlow and the underground city at Olduvai, believing that their unique insights and knowledge would be useful to the company someday. To Pryce and Wey-Yu, the moon-wide infestation was a useful opportunity to acquire valuable data, samples, Xenomorph specimens, and Marlow's research without the need to take any responsibility for the disaster (they could simply blame Marlow as a renegade ex-employee). Unfortunately for Pryce, Hayes realizes all this and comes to the conclusion that Pryce is just as responsible for the Xenomorph infestation as Marlow and the Darwin Era cult, resulting in her leaving Pryce to the tender mercy of the Xenomorphs.
• Not Using the "Z" Word: In Aliens: Fireteam Elite, which takes place just a couple of years after this game, xenomorphs are common knowledge. Here, no one seems to have ever heard of them, and characters generally refer to them in vague terms such as "those creatures".
• Optional Stealth: Outside of scripted moments, missions alternate between times when the Hive hasn't been alerted to the marines' presence and times when it has. When a xenomorph spots the marines, the Hive jumps into action, rushing the marines with every xenomorph present. Every time this happens, the Hive aggression meter gradually rises, with Category 2 Xenomorph spawns and Onslaughts at certain thresholds. Further, the higher the Hive aggression, the more xenomorphs they send against the marines. This gauge will only go up until the marines extract and it resets. Hence, while stealth isn't strictly necessary, it is useful in keeping from being overwhelmed during a mission.
• Papa Wolf: Once he learns that his daughter Cassandra may still be alive on Lethe, Harper becomes determined to rescue her, come hell or high water. On the verge of death inside the Otago, Harper uses his unique alien telepathy (shared with his daughter) to momentarily distract an ancient Xenomorph Titan underneath Olduvai, enabling Cassandra and Maeko Hayes to escape. Unfortunately, the mental strain kills the already weakened Harper.
• Plasma Cannon: Available as a primary weapon for marines who've maxed out their level. Compared to pulse weapons, it does more damage and is capable of an "overcharge" attack that blasts a large amount of energy out that does continuous damage in a straight line but necessitates that the marine so equipped switches to their sidearm while it cools back down.
• Quarantine with Extreme Prejudice: After barely surviving the Xenomorph infestation of Pioneer Station, realizing that the transport Bentonville was also infested and lacking any other means to prevent the Bentonville's departure, Hayes activates the Cerebus Protocol to initiate a quarantine of Lethe and its low orbit. The Bentonville is destroyed and the Xenomorph infestation is prevented from spreading outside Lethe, but it traps any and all survivors on the infested moon, including the crew of the Otago. Unknown to Hayes, the Cerebus Protocol will eventually reach Stage 2, the point where the entire surface of Lethe will be sterilized via nuclear bombardment. By the time a USCM squad infiltrates the infested Pioneer Station to undo the Cerebus Protocol, it's too late to deactivate them.
• Quit Your Whining: The sergeant class' "Reprimand" ability, which suppresses all stress build up for a short period of time. Essential in the mid and late game to keep marines heads in the fight instead of freaking out.
• Race Against the Clock:
  • The planet's infestation level steadily increases the more time passes, increasing the difficulty of each location.
  • About halfway through the game Weyland-Yutani will start a countdown to sterilizing Lethe with a nuclear bombardment. At that point you need to complete the main quest before the countdown reaches zero, or else the Otago will still be on the planet when the surface gets vaporized.
• Religious and Mythological Theme Naming: To Greek mythology in particular.
  • The moon Lethe is named after one of the rivers in the underworld, said to make those who drink from it forget.
  • The Cerberus Protocol is named after the three-headed hound of Hades, who guards the gates to the underworld and makes sure none get out.
  • Cassandra is named after a seer who had the ability to peer into the future, but she was cursed such that no one who heard her would listen to what she said.
• Salt the Earth: Stage 2 of the Cerberus Protocol is essentially this, as the first stage simply eliminates all potential possibility of escaping Lethe by blowing any vessel past a certain threshold of the planet's atmosphere; but Stage 2 is about ensuring that nothing that is registered as a threat — which in this case is a planet-wide Xenomorph outbreak — survives on the planet surface with a sheer blanket of nuclear fire across every nook-and-cranny of the planet's crust until it is completely cleansed of everything.
• Sanity Slippage: As part of the Morale Mechanic of stress, allowing a marine's stress levels to exceed the 100% threshold will cause them to start slipping with a variety of negative possible effects such as reducing their accuracy, expending more ammunition than necessary, or reducing command points as they begin to crack under the pressure. Allowing the stress to hit 100% again after that produce even more drastic effects. Hitting any of these thresholds will cause them to develop traumas, all of which produce a permanent negative effect on the marine, which will need to be treated aboard the Otago to restore them to optimal performance.
• Scavenger World: Lethe wasn't always this, but since you're living out of a crashed ship, you need to spend as much time raiding the remains of the colony as you do scouting for enemies.
• Screw This, I'm Outta Here:
  • Harper reveals that he is a Lethe native. However, the conditions of his colony were so horrible that he signed up with the USCM just to get away, leaving behind his daughter.
  • Something mechanically implemented in the game as well. Marines can extract mid-mission, with the mission being resumed during another deployment. Usually this will be because the marines are too stressed, too injured, too low on supplies, the Hive is too worked up, or any combination of the above.
• Self-Duplication: The Big Bad and leader of the cult, Dr. Marlow, sick of Wey-Yu office politics, ultimately decided the only person he could trust was himself, and thus created a few dozen Synth clones of himself to serve as his assistants. At the end of the game, you learn the real Marlow died from chest-bursting long ago, and his Synth copies have been continuing his work since then.
• Sensor Suspense: The motion-tracker carried by the squad is the primary means of early warning about threats, and its coverage can be extended with deployable motion tracker modules that can be emplaced around the map. Dodging around these sensor blips to avoid being prematurely spotted is a major part of the moment-to-moment maneuver gameplay.
• Sentry Gun: A common piece of equipment, with each marine in the squad able to lug one around. They take time to deploy or pack up, have a limited fire arc in their front quarter, and need to be periodically reloaded. However, they do significant damage and overlapping fields of their fire can chew targets into fine chunks with dependable reliability. Mission success often rides in knowing where and how to place these guns to give the marine squad the edge it needs to get by.
• Sequel Hook: After the Otago escapes Lethe, Maeko Hayes, Cassandra Harper, and the surviving crew enter cryosleep as the ship begins to travel across deep space. According to Director Pryce, the Otago's computers contain what's left of Marlow's research (through Dr. Becker's examination of a Darwin Era Guardian and the Chestburster inside him), so it's likely that Weyland-Yutani will be very interested in recovering that research at any cost.
• Short-Range Shotgun: A starting secondary weapon for marines. It can be fired to hit one or more targets in a short cone in front of the wielder, and targets closer to the point of the cone will take more damage than those further out. Despite being the default special weapon unlocked at first level, the tendency of xenomorphs to rush into melee means it retains its utility even into the late game.
• Shout-Out:
  • As usual, to Joseph Conrad. The Otago was the ship that Conrad himself captained, and of course the name "Marlow" is a reference to Conrad's recurring character Charles Marlow, best known as the viewpoint character in Heart of Darkness.
  • Also to The Fast and the Furious in the form of a datapad in the atmosphere processor basement addressed to a "Dom" inquiring about help fixing up a vehicle. Because they're family.
• Smart Gun: The original trope-namer is the primary weapon of the gunner-class marine. At its base level it's simply an automatic man-portable support weapon. With the appropriate upgrades, it adds a thermal-targeting system that drastically ups the weapon's accuracy against user-designated targets, high-impact rounds that increase the pinning effectiveness of suppressing fire, and a tripod that allows the smartgun to be deployed on its own as a self-targeting weapon out of the operator's hands.
• Stealth-Based Mission:
  • In the tutorial, Maeko is controlled directly and is unarmed save for an under powered sidearm that she lacks combat experience with. She must sneak past a xenomorph rather than engage it head-on.
  • When one of the creatures is loose aboard the Otago and all the marines are either injured or on deployment, Maeko has to try to dodge being spotted by it and lure it into traps in order to contain it.
• Stupid Evil: The Weyland-Yutani corporation betraying the colonial marines was very foolish. The USCM were very useful allies, and instead of working together as allies, they began fighting each other as additional enemies. Even if they were going to betray them, it should have been as a You Have Outlived Your Usefulness after they were off the planet that was going to be nuked from orbit.
• Suspiciously Cracked Wall: Present and can be destroyed with C4 deployed by one of the marines in the squad. This usually leads to extra resources or offers a flanking opportunity. However, the noise of the detonation may also attract the attention of nearby xenomorphs.
• Tactical Door Use: Enemies can normally go through doors, but your marines can weld them shut (or cut them open again). If you seal off an entire room with welded doors, your squad can take a break and regroup, lowering their stress levels.
• Took a Level in Badass: Originally a dutiful Weyland-Yutani administrator, Hayes takes on the role of an officer aboard the Otago despite her lack of military experience, directing the USCM squads on Lethe with advice from Harper. She gradually earns the respect of the Otago crew and becomes more determined and resourceful, culminating with her taking direct command of the crew herself after Sergeant Harper dies. Hayes completes this by going on the last field mission herself and wearing a USCM uniform.
• Token Good Teammate: Deputy Administrator Maeko Hayes is just about the only Weyland-Yutani higher-up on Lethe who isn't either massively corrupt or Machiavellian evil. Stern also is an example, as one of the few morally conscionable mercenaries working for Weyland-Yutani who ends up inevitably betraying the company to help out when they start creating far more problems than they are solving to cover their own asses.
• Underground City: The Precursor city beneath the Olduvai mine on Lethe, where the alien eggs were discovered. Why it is located here or what its purpose was is unknown, though the fact that it's located beneath the single largest trimonite deposit on Lethe suggests it may have been placed where it was for the sake of concealment.^note In the Alien universe, trimonite is the hardest mineral known to humanity and is heavily opaque to many kinds of sensors.
• Unwitting Instigator of Doom: Doctor Bookard is a compassionate doctor who is so unwilling to abandon even a single life that could be saved that she ignores an alert to evacuate to the armory. Unluckily for her, that alarm was because a Xenomorph was on the loose. Her death also means that far less well trained medics are now forced to step up, and they outright admit that without her they aren't able to stabilise Harper, leading to his death as well.
• Villainous BSoD: After Hayes leaves Pryce's office alone after giving the director a "The Reason You Suck" Speech and accusing her of not being human, Pryce repeats the words, "I am not a synth...", gradually fading into an inaudible whisper. Hayes' speech having reached her, Pryce struggles with both her newly emerging guilt and her Blind Obedience to Weyland-Yutani.
• Vocal Dissonance: The Darwin Era Guardians are creepy cyborg-human-alien hybrids, and the one Guardian you speak with in a cutscene has an appropriately creepy voice, but in-game they use the same "space redneck" voice set as the normal Darwin Era cultists, which can be unintentionally humorous.
• Wrong Genre Savvy: The Darwin Era cultists aren't completely stupid/insane in wanting to feed themselves to the xenomorphs. The rank-and-file grunts believe (wrongly) that the xenomorphs are transformed humans, and that they too can become "Ascended" by being selected by the xenos. The cult's leader, of course, knows that this is complete bullshit, but sees it as a useful way to control the cultists and obtain willing test subjects for his alien-hatching experiments.
• X-Ray Vision: One of the upgrades for recon-class marines is a set of thermal goggles that allow them to spot enemies through walls for a range of several meters. While the motion tracker is the primary means of situational awareness, it only works on moving enemies, and these help spot ambushes from still enemies such as a sleeping drone on the other side of a cargo crate or alien eggs placed just on the other side of a door.
• You Are in Command Now: By the time Hayes arrives on the Otago after it made an emergency landing, its officers have either perished or abandoned ship, leaving the most senior NCO, Sergeant Jonas Harper, in charge. In the final stages of the game, Harper's worsening visions about his daughter Cassandra and the Xenomorphs gradually overcome him and leave him unfit for command. With Hayes having proven her worth by this time, Harper designates Hayes as next-in-command.