In Priority: Tuchanka, you are offered a choice between curing the genophage and gaining krogan support, but losing the support of the salarians, or sabotaging the cure and retaining salarian assistance. It is possible to gain the help of both. One of these options is if Wrex is already dead. It's still possible to gain the help of both even if Wrex is alive and you cure the genophage. If Kirrahe survived the events of the first game, AND the Cerberus attack on the Citadel, he'll rally support, oppose the dalatrass, and gives you the support you need. If Kirrahe didn't survive, but Mordin sacrificed himself, the STG will rally to support in honor of Kirrahe and Mordin, but it'll be less than what the dalatrass promised.
A Spectre named Jondum Bau asks you to stop an indoctrinated hanar. However, the hanar uploads a virus that will take out the defense systems of Kahje, the hanar and drell homeworld, and has a human accomplice strangle Jondum Bau so Bau will not be able to stop the virus. That forces you to choose between either taking the Renegade Interrupt and saving Bau from the accomplice (which gets you a Spectre Unit from Bau but costs you Kahje), or not taking the interrupt and stopping the virus (which gets you Kahje's support, but costs you the Spectre unit). The third option requires you to download the Kasumi Goto DLC in Mass Effect 2. If Kasumi survived the Omega-4 Relay, she will stop the indoctrinated hanar's virus, and Shepard will automatically save Bau, though she dies (or at least, fakes it without telling you) in the process if her loyalty mission in the second game wasn't completed.
Din Korlack, the unpleasant volus ambassador from the first Mass Effect game, is kidnapped by bounty hunters for his past work with Cerberus. After you save Din from the bounty hunters, Shepard will ask Din to give him/her the location of the turian colony about to be attacked. Din will demur and offer you the Volus Bombing Fleet as a bribe so that his culpability will not be revealed and Cerberus will not know he betrayed them. The Paragon choice is to save the turian colony, but this just prevents a loss in War Assets. The Renegade choice is to accept the Volus Bombing Fleet, but this will result in a loss in one of your turian War Assets. However, if you downloaded the Zaeed Massani DLC in the previous game, and he survived the Omega-4 Relay, and he's still loyal, Zaeed will be part of those interrogating Din but will kill the bounty hunters upon Shepard's arrival, and you can persuade Din to give you the information and the bombing fleet.
Genesis 2 doesn't give you a few "outs" you'd get by actually playing the second game — for instance, you can't upgrade the Normandy in advance of going through the Omega-4 relay. If you go through immediately, you lose squadmates. If you wait and make upgrades, you leave the crew to the Collectors.
Sawed-Off Shotgun: No one saws off the barrel of the mass effect enabled linear accelerators which function as guns in this setting, but the AT-12 Raider certainly comes close to duplicating the function of one. It is a shotgun with only two shots before it needs to swap the thermal clip, and a lot of wide spread when fired, but those shots hit hard. Perhaps unsurprisingly, it is a weapon of batarian manufacture.
Scenery Gorn: Everywhere at all times where there are Reapers. A glimpse of Palaven from one of its moons, for example.
"From Ashes" reveals that Eden Prime is beautiful when it's not being devastated by a geth attack.
The mission to Menae, the moon of the turian homeworld Palaven, is essentially an excuse for a nice, long scenery porn run, as you wander down canyons that end at magnificent vistas of the burning planet, Reapers walking across the surface, and lovingly-detailed shots of crashed turian ships. The amount of destruction also overlaps with Scenery Gorn.
If you take EDI with you on the Sur'kesh mission, she will note that the view from orbit isn't as spectacular as the view on the ground. This may be because the physical perspective of an organic sapient-sized body is a new experience for her.
Schrödinger's Butterfly: After leaving the Geth Consensus, Joker will posit the theory that you never left, and that everything you are seeing is just a part of the simulation.
Science Is Bad: Apparently, this is the aesop the Reapers embraced. They came to the conclusion that organic civilizations would ultimately destroy themselves by creating synthetic life, so the best way to preserve their existence was to convert them into Reapers before their science reached such a point.
Sci-Fi Writers Have No Sense of Scale: The War Assets in Mass Effect 3 aren't really consistent with scale. Certain assets have an oddly disproportionate effect on how they impact your total assets, such as individual, exceptional characters, ships, or small infantry units having as much impact as entire military divisions or fleets. Others are reserved specifically for either scientific work on the Crucible, or for the final assault on London, but even then have a disproportionate impact, such as four individuals and a cruiser having as much impact as hundreds of quarian heavy warships.
One caused by a minor continuity error: The war assets for the turians references a Cerberus Daily News column where the War on Taetrus was sparked by the turian separatist group Facinus crashing a ship into Vallum, killing 100,000. The entry says that the suicide ship was crashed into the planet at FTL speeds. If it was going that fast, it should've snapped the planet in half, not damaged one city. It was not actually moving that fast, according to the CDN article, which specifies that the ship was beginning the acceleration to FTL speeds and that it only impacted at roughly the velocity of a single mass accelerator round.
In the multiplayer mode. Unlike most cases of this trope, the points have a purpose; at the end of a match, each player's individual score is added up, and the total is converted into Experience Points and given to each character.
In the single player CitadelDLC, the player is given the option to participate in the Armax Arsenal Arena, a holographic combat simulator where the player may set up matches for viewers' enjoyment. Rewards are based on score, and score is based on a combination of how well they play and how difficult the match is. The rewards are tokens to unlock more content in the Arena, but they can also be redeemed for credits.
Vega and Cortez bicker over the merits/flaws of the Mako and Hammerhead. Vega says the Hammerhead practically has armor made of paper, while Cortez complains that the Mako "handles like a drunk rhino."
Conrad gets a full minute plus discussion with Shepard about thermal clips.
Conrad: I dunno, seems like a backwards step to me. You can still let the guns cool down themselves though, right?
Shepard: Ehh, no. They had to remove the self-cooling systems to make room for where the clips go.
Conrad: Oh, well that's just... You might as well just go back to limited ammunition!
Self-Fulfilling Prophecy: The Catalyst judged that synthetics would try to destroy their creators, so he decides to harvest the very race that create them. Of course, due to its Blue and Orange Morality, it doesn't consider this action actual aggression against its creators.
The whole quarian/geth conflict also turns out to be one.
At the end of the Ardat-Yakshi monastery arc, Samara attempts to commit suicide to save her daughter Falere from her Code, which demands her death. Shepard can let this happen, and still kill Falere for being a threat.
Can be turned Up to Eleven with Rannoch. One end to Rannoch's arc results in saving the geth and sacrificing the quarians, Tali included. Legion also dies to give the geth true consciousness. One of the endings to ME3 destroys the Reapers, but at the expense of wiping high-end synthetic life like the geth, thereby rendering Legion's sacrifice and Shepard's deliberate sacrifice of the quarians pointless.
Sequel Difficulty Spike: According to BioWare, this game would be harder than the first two, with "Normal as the new Veteran." True to that statement, there is no longer a Veteran difficulty level; it progresses straight from "Normal" to "Hardcore."
The Stingerreveals that the entire trilogy was being recounted to a child by his/her grandfather. He promises to tell them "one more story about the Shepard" before the screen fades. A message follows about Shepard "becoming legendary".
Provided your War Assets were high enough, Shepard wakes up at the end of the "Destroy" ending.
Serious Business: In "Citadel", Zaeed becomes obsessed with a claw game in the casino.
Traynor also gets her moment of this in the same place, squaring off against her Archnemesis at... Space Chess. Even her dental hygiene is implied to be this, with her toothbrush that uses mass-effect fields to remove plaque.
Sexy Walk: Averted a number of times in the game, as female characters, particularly the Normandy crew, will often be seen moving in a noticeable masculine manner (suggesting the same motion capture was used whether you choose a male or a female character to accompany you on missions). There are notable exceptions during cut scenes when it's necessary, and in the Citadel DLC when Liara meets you in the auto dealership and later if she accompanies Shepard to the casino she is animated to walk a lot sexier than she usually does (see for example, after she convinces the auto lot attendant to open the gate).
Shadow of Impending Doom: The Reaper destroyer on Tuchanka can kill you if it stomps on you. A shadow will form on the ground about two seconds before its leg hits, so you'd better get out of there fast.
Mysterious Figure: You're just cybernetics! Scarred, worn-out Cerberus tech!
Shepard: You know where I got those scars? Feros and Noveria and Virmire and Ilos! At the Collector Base and Palaven and Tuchanka and Rannoch and Thessia! I earned these scars protecting the galaxy! You got yours from a petri dish!
Sigil Spam: Cerberus, who badly abused this trope in Mass Effect 2, now take it to the next level. The inside of their 'secret' bases, their weapons, their armour, and their vehicles are stamped with their logo, and all their soldiers sport the distinctive black, white and yellow paint job. Justified since Cerberus is done with secrecy, unleashing the full might of their forces on the galaxy to fulfill the Illusive Man's final plan.
Simple Yet Awesome: The Mantis sniper rifle, which is the first sniper rifle unlocked in singleplayer and multiplayer. It's a near-hitscan weapon with great damage and the lowest weight of all sniper rifles. Coupled with an Engineer who can score consistent headshots, it becomes one of the best weapons ingame.
Slap-Slap-Kiss: If you romanced Jack in ME2, she will punch Shepard in the face before giving him a passionate kiss.
Slave Mooks: Though the Reapers have always had the husks, it is eventually revealed that most Cerberus troopers are this too, as Cerberus managed to raise such a large army in the six-month gap between the second and third games by kidnapping civilians and using Reaper implants to indoctrinate them.
Smoke Out: CAT6 snipers in The CitadelDLC throw smoke bombs at their feet when foes draw near, then activate a Tactical Cloak to slip away in the confusion to re-engage at a more favorable distance.
Sniper Pistol: Gun customization means you can, well, add a sniper sight to your heavy pistol. The proper modifications on the proper pistols effectively make them into a lightweight, mid-range sniper weapon. The Carnifex works well for this, and the Paladin works even better. The Executioner, a mother-of-all-handcannons with a muzzle bore diameter that's probably a good inch across and added by the Groundside Resistance DLC, works best of all.
Sniper Rifle: Standard equipment, coming in models that offer armor-piercing capability and with attachments that let you see through smoke.
Socialization Bonus: Your War Assets, which build up via both plot and sidequest, are assigned point values, the way they might be in Tabletop Games; Miranda Lawson, as an example, is worth 25 points all on her own. Those bonuses add up to help the final battle go better and provide a better outcome. However, each asset's value is modified by their "efficiency" rating, measured in a percentage that goes up with multiplayer victories: base War Asset value times the Efficiency percentage equals "Effective Military Strength," which is the number that really counts. A 1,000-point army at 100% efficiency has the same EMS as a 2,000-point army at 50%.
Sociopathic Soldier: The CAT6 mercenary group from "Citadel" consists of ex-soldiers who were dishonorably discharged for criminal behavior.
Somebody Set Up Us the Bomb: Used on Sur'Kesh, during the extraction of 'Eve'. Shepard and co. call an elevator to head for the surface... only to find that Cerberus left a present. Naturally, everyone survives, except an STG Red Shirt standing too close when the doors opened.
Someone to Remember Him By: Ereba, the asari whom you possibly convinced to rekindle her relationship with her krogan boyfriend, is pregnant by the time of this game. Unfortunately, Charr dies fighting Ravagers and Swarmers during the war.
Something Completely Different: The mission where you enter the geth consensus which does not include any fighting, but instead involves solving some (admittedly fairly simple) puzzles, wrapped up in a new visual style.
Two missions in the Leviathan DLC have you looking for clues to narrow down a search filter to locate planets of interest.
If Shepard has the Spacer background, Hackett informs Shepard that his/her mother is still alive, promoted to Rear Admiral, working on the Crucible, and that "she's damn proud of what [s/he's] doing out there."
Also said by Shepard's mother when you call her during the Citadel DLC.
Said to Shepard in the ending sequence by the dying Admiral Anderson.
You did good, son/child. You did good. I'm proud of you.
Space Battle: Quite a few happen over the course of the story, most referenced in passing or seen from a distance, but several put you right in the midst of it.
Space Is Noisy: Handwaved; Steve Cortez twice refers to "auditory emulators" to explain why there is noise in space; he mentions that he sometimes turns them off so that he can watch ships go by in complete silence.
And played with during the final battle scene. We go from the opening barrage of mass drivers from the fleet approaching Earth, to a large formation of fighters closing the intervening distance. Once the scene begins to follow the fighters, all you can hear for a few seconds is the whine of starfighter engines before they engage the Reapers directly.
Spent Shells Shower: The N7 Typhoon is a light machine gun which fits in the assault rifle slot and is one of the heaviest regular weapons a character can wield. It is capable of generating a ridiculous amount of dakka, and has spent bits continuously flying out of an ejector port while it fires. It might seem illogical that a weapon that fires ammunition shaved from solid block has casings, but closer inspection reveals that they are not "casings" at all but individual cells from the many thermal clips the weapon requires, ejected as fast as possible to keep it cool.
Species of the Galaxy Montage: The extended cut shows other worlds fighting the Reapers and celebrating their victory, specifically the homeworlds of asari, turians and krogan. In the epilogue you see brief glances of even more worlds.
Spider Tank: Reaper Destroyers, the go-to heavy ground-based combat unit for their forces. It's roughly 1/4 the size of the actual Reaper ships, which still puts it far into Humongous Mecha territory.
Spotlight-Stealing Squad: Liara is required for three missions (four, if the From Ashes DLC is played), and is given many scenes with Shepard that other characters will not have. Before the Extended Cut, Liara is the last person Shepard thinks about if his romantic partner was not Ashley or Kaidan. In the Citadel DLC, Wrex does this on a slighter scale. While Shepard is still the star, Wrex still gets more dialogue than the others, and talked up at how great he is by the others.
Squee!: Joker kids about this pertaining to Liara and first discovering Javik.
Joker: So, a real live Prothean, huh? Has Liara stopped bouncing? I'm guessing there was bouncing.
The Adept. Even with all of the fitness tree upgraded this class is by far the least durable of them all in terms of hit points and resistances. It makes up for this with having incredibly useful abilities like Stasis or Singularity that is exclusive to the class. This is also helped by an extremely fast recharge rate from using light weaponry. Liara, essentially being a character-specific "adept" class, is somewhat lacking barrier points and greatly lacking hitpoints.
The Drell in multiplayer. Low hitpoints, lowest shields in the game- but very speedy, and very wizardly.
The Volus in multiplayer. A normal amount of shield points but a pitiful 150 hitpoints and only average Fitness bonuses. However the Adept is a surprisingly powerful offensive character and the Engineer is now a cornerstone of defensive strategies with its support abilities.
Star-Crossed Lovers: An in-universe fictional example: Shalei, a quarian, and Bellicus, a turian, protagonists of the movie classic Fleet and Flotilla.
Stealth-Based Mission: Of a sort. When traveling on the Galaxy Map, you have to be careful while exploring a system under Reaper control. If you draw too much attention to yourself (by doing an excessive amount of scanning), then a number of Reapers appear to attack your ship, forcing you to flee.
Stealth Hi/Bye: A little boy vanishes around a corner silently while Shepard looks away momentarily, and s/he does not notice.
The appropriately-named Sticky Grenade, the Infiltrator-specific grenade power. It can be upgraded to blast through armor more effectively, as well as to arm itself on a timer and serve as a proximity mine should it fail to land on a target.
The Scorpion (Kirrahe's pistol during the Sur'Kesh mission) shoots lower-powered versions of these.
Dr. Eva is impossible to kill during the chase sequence, as her shields instantly regenerate when damaged. This is necessary as her "body" is needed for later in the game when EDI takes it over.
On Thessia, Kai Leng cannot be touched when the gunship is covering him.
Strawman Fallacy: Present in the Rannoch and Tuchanka arcs. Admiral Han'Gerrel and Dalatrass Linron are both horrible people; racist, sociopathic, hypocritical bullies. They represent the Renegade options for those arcs, wiping out the geth and not curing the genophage respectively. They don't seem be driven by genuine belief that they are eradicating an evil, or logical pragmatic conclusions that one could plausibly reach when considering these morally grey subjects, they're just doing what they do to spite the geth and krogan because they're space racist, and even willing to sacrifice millions if not billions of innocents for that goal.
There's also Lieutenant Tolan, who takes Kirrahe's place if he died in the first game. He's one of the only characters who argues against curing the genophage, and of course he does this using arguments that are easily shot down by whatever squadmate Shepard brings with him/her when talking to Tolan. He also acts rude and condescending his conversation with Shepard, refusing to even shake his/her hand because s/he doesn't treat the krogan like animals.
Strictly Formula: The way enemies work in the game, generally with one (sometimes two) of each enemy type per faction.
Foot Soldier: Basic enemy types with ranged weaponry and no shielding.
Cerberus: Assault Trooper
Geth: Geth Trooper
Collectors: Collector Trooper
Commanders: Slightly more powerful than foot soldiers. Have shielding in addition to health. In most cases have a way to buff their teammates.
Geth: Geth Rocket Trooper
Collectors: Collector Captain
Cover Busters: Enemies who will Zerg Rush your position and force you out of cover. Either melee only or have very short range attacks.
Cerberus: Guardians and Dragoons
Geth: Geth Pyros and Geth Bombers
Elite Mooks: More powerful than most enemies you face and tend to be fairly uncommon. Usually short ranged, similar to Cover Busters. Some have melee only One-Hit Kill attacks.
Geth: Geth Hunters
Bosses: Appear rarely. Tend to be very powerful with strong attacks and usually have a short ranged One-Hit Kill attack.
And again with Blasto 7, which Shepard and Javik get tricked into making cameo appearances in the Citadel DLC.
Sufficiently Advanced Alien: During the Thessia Mission, it turns out that the asari goddess Athane was a visualization of the Protheans, and her miracles the efforts to uplift the asari race, including teaching them how to write and farm. If Javik is present, he will call Liara out on her initial disbelief, until she is finally convinced.
Summon Bigger Fish: Plan A for dealing with the Reaper destroyer on Tuchanka is a two-pronged assault by krogan armor and turian fighters. Plan B? Using the maw hammers to summon Kalros, the "mother of all thresher maws." It actually works better than they'd hoped: instead of merely distracting the Reaper, Kalros outright kills it.
Suspiciously Similar Substitute: Several instances occur throughout the game, based on who lived and died in any one person's particular playthrough throughout the series. If certain squadmates from ME2 died in the suicide mission, other characters may fill in for some of them where they are supposed to appear.
If Mordin Solus died in the Suicide Mission in ME2, Padok Wiks (the Special Tasks Group commander on Sur'Kesh) assumes his role in the narrative, and can fulfill exactly the same role as Mordin. The game even calls attention to it — Joker takes to calling Wiks "Not-Mordin."
If you did not spare the rachni queen in the first game, a queen appears in the rachni hive and can also be recruited if the player chooses. However, this has a nasty consequence; this queen has been created by the Reapers, and it and its children run rampant on the Crucible and cause several deaths before they are put down, giving a reduction to your War Assets.
If Grunt did not survive the Suicide Mission, his role is replaced by Urdnot Dagg, another krogan picked (by either Wrex or Wreav) to lead Aralakh Company. Unlike Grunt, however, Dagg always dies at the end of the mission.
If Legion did not survive the Suicide Mission or he was sold to Cerberus, his role in the geth-quarian War will be assumed by a nondescript "Geth VI" constructed in Legion's likeness. Shepard will even note that the VI looks very similar to the geth they retrieved in the previous game if Legion was never turned on. This does not count Legion's appearance as a "Geth Assassin" at the Cerberus Base if you sold him previously. It is also impossible to achieve peace with the Geth VI.
If Tali did not survive the Suicide Mission, then Admiral Daro'Xen will replace Tali's role in the Geth Dreadnought mission, and Admiral Shala'Raan vas Tonbay will replace Tail's role in the Rannoch Reaper Base mission. And just like Tali, Raan kills herself if you allow the geth to wipe out the quarians. Unlike Tali, though, Raan doesn't jump off a cliff; she shoots herself in the head, and unlike in Tali's case there is no "fake Paragon interrupt" to attempt to stop her. Also, just like Tali, Raan will kill Legion if you allow the quarians to wipe out the geth; unlike Tali, instead of using a knife, Raan just shoots Legion and you won't get a Renegade interrupt to shoot Legion yourself three times.
Supporting Leader: Several, including Urdnot Wrex (or Wreav), the members of the quarian Admiralty Board, and Primarch Victus as you try to get entire alien races to unite and assist Earth. Holding down the fort until these allies can show up are Admiral Anderson, who stays behind on Earth, and Admiral Hackett, who seems to be the de facto leader of the joint species fleet in the end.
Sword and Gun: In addition to the standard two-gun carrying capacity, N7 Shadows and N7 Slayers come equipped with mono-molecular-edged swords on their backs that they draw to preform their melee attacks.
The mission to cure the genophage can result in gaining support from either the salarians or the krogan. Depending on your decisions in past games and your later actions in this game, it is possible to gain the support of both after the Cerberus attack on the Citadel.
During the geth/quarian conflict, you are forced to choose one side over the other, with both sides promising various things. Depending on what you did in previous games, Shepard can choose to save both races instead of letting one side or the other get wiped out.
The lead-up to the endings sees Shepard, Anderson and the Illusive Man arguing over whether or not to destroy the Reapers or take control of them. The Catalyst itself can possibly provide a third option: to make the entire galaxy a synthesis of organic and synthetic life, causing the Reapers to cease hostilities. In the Extended Cut, Shepard can take a fourth option: Refuse to take any of the Catalyst's offered choices in defiance of its claim to know the destiny of organic life. All space-faring life is wiped out, leaving Liara's warnings for the next Cycle.
Shepard pulls a variation of this towards a traumatized little boy. In this case, the boy is not in any immediate danger beyond being on Earth as the Reapers invade, Shepard is simply trying to get the boy to trust him enough to let him take the boy to safety. The boy declines.
"You can't help me."
A conventional example can be found while on the geth dreadnought, where Tali saves Shepard from falling to his/her death when the elevator is damaged by a rocket.
Subverted on Rannoch, where siding with the geth will cause Tali to jump off a cliff. Shepard runs towards her, a Paragon Interrupt flashes onscreen... and Shepard arrives a moment too late.
After defeating the Clone in the Citadel DLC, Shepard will offer a hand if you take the Paragon option. The Clone refuses, not having a reason to live.
Take Up My Sword: The task of developing and building the Crucible has been passed on through countless cycles of reaping, each one contributing new discoveries about the Reapers and new technological inventions to make it into a working weapon against the Reapers.
At the conclusion of the Poisoned Medigel mission on the Citadel, Conrad will do this for Shepard, complete with a dramatic slow-motion dive. If you completed Jenna's sidequest in the first game then he is not shot after all.
If he survived the Virmire mission in the first game, and Thane did not survive the suicide mission in the second game, Major Kirrahe will take the bullet for the salarian councilor during the Cerberus invasion of the Citadel instead of engaging Kai Leng in combat.
Taking You with Me: The turian and krogan insurgents during "The Miracle at Palaven" who sacrificed their lives guarding the ship-busting bombs they smuggled inside the Reaper ships.
"Unless we're planning to *talk* the Reapers to death, the committee is a waste of time."
Team Pet: KEI-9 in the Collector's Edition, who is a robotic dog that was left behind by an Alliance engineer during the Normandy's retrofit, and exists to walk around in the ship's shuttle bay and be referred to by Shepard as a "good dog".
Technicolor Eyes: For the first time in the trilogy, Shepard is not restricted to the standard range of human eye colors but can have more exotic iris colors like white or red. In the Synthesis ending, everyone gets glowing eyes (as well as very faintly glowing dermal-circuitry) depending on their original iris-color (though in the ending slides they're all just green, presumably as visual shorthand). Joker's are bright green, Liara's are bright blue, Traynor's and Kaidan's are bright gold, James and Ashley get shimmering bronze-gold, EDI has teal and so on.
Teleportation: The multiplayer N7 Slayer and N7 Fury characters are capable of this over short distances. Walls are no object, as long as there is a safe space to exit on the other side. Their melee attacks are also teleport-based.
All Vanguards but one can also teleport using Biotic Charge, although this requires an enemy in sight to teleport to. Same goes for the N7 Shadow.
Wrex: This is why I love hanging out with you guys. Why shoot something once, when you can shoot it forty-six times?
The World Is Just Awesome: During the Casino job in the Citadel DLC, energy mogul Jonah Ashland comments about how nobody's distrustful of other races anymore, and that if the war is won, the galaxy will be a pretty great place (presumably after cleanup).
Javik threatens to do this to Joker after being continually referred to as "Prothy The Prothean". He's also in favor of spacing Legion due to his views on synthetics.
If you sabotaged the genophage cure and Wrex is the krogan leader, you will need to kill him on the Citadel when he discovers your betrayal. Bailey will tell Shepard that they will have to do this to Wrex's body, as they simply do not have time or resources for a funeral or even a coffin large enough to fit him.
Shepard him/herself is not averse to this: During the Citadel DLC archives, after being trapped in a vault, you get to talk to the Big Bad, Shepard's clone, and Maya Brooks, threatening to take both their heads and mount them in the CIC, and then invoke the trope. Javik approves.
Time Abyss: The Reapers have been active for billions of years. The Catalyst is older than the Reapers themselves and has watched countless cycles of life evolving and being destroyed.
The Leviathan DLC reveals the Leviathans have been around even longer than the Catalyst (considering they created the Catalyst, which then turned on them). They've apparently spent those billions of years passively watching every harvest and mastering the game of Hide & Seek.
Timed Mission: Tuchanka: Bomb has to be completed within three missions of getting them or they're automatically failed. The Grissom Academy mission is automatically failed if you don't do it before Priority: The Citadel II. In a different vein, when attacking the Cerberus space station, you have only a little more than a minute from EDI telling you that they're going to vent the hangar before they do so. That last is very easy to avoid — if you do realize that for once the squad's banter about urgency actually holds water and find the ladder.
Tiny-Headed Behemoth: The Brute is a husk composed of krogans and turians that has a small head on a stalk, attached to an enormous ape-like body.
Tired of Running: Shepard accidentally woke up a Reaper tank and their first response is to just get away, but Shepard realized that by running all they would do is delay a massive battle and more lives will be lost because the Reaper was controlling/influencing the geth forces. So s/he decides to stand his/her ground and calls in the Migrant Fleet for a precision orbital strike.
Tomato in the Mirror: Maybe. Near the end of the game, Shepard watches some videos in the Illusive Man's base that confirm that, yes, s/he really was brain dead and wonders, "Maybe I'm just a high-tech VI that thinks it's Commander Shepard?" Whichever squadmate is with you at the time will vehemently disagree with the notion.
The case for Shepard being the original is more likely since they retain the Prothean Cipher, which was implanted in their subconscious. Furthermore, an actual Clone!Shepard appears in the Citadel DLC who doesn't share their counterparts memories and laments that the Illusive Man preferred to bring back a corpse rather than a copy.
In Mass Effect 1, your four alien crew members were a mercenary (Wrex), a C-Sec operative (Garrus), an archaeologist (Liara), and a wandering teenager (Tali). By the time you hit this game, those same characters have become the de facto leader of the krogan race, a notorious ex-vigilante and commander of a special military unit, the Shadow Broker, and an Admiral of the quarian Flotilla. Not to mention that your fellow human goes from Lieutenant/Gunnery Chief to Staff Commandernote essentially outranking you/Lieutenant Commander and becomes the second human Spectre. Damn.
Too Soon: In-universe. When Thessia falls, Joker cracks a half-assed joke. Shepard is not amused.
Trash the Set: That fancy field-of-stars office the Illusive Man communicates from? It will suffer heavily during your final fight with Kai Leng.
One of the most memorable changes in the Extended Cut DLC is transitioning the original ending's somber/tragic theme, "An End Once And For All", into a version that actually makes you feel victorious, assuming you've accumulated enough war assets to prevent the Normandy from being stranded.
True Companions: Explicitly mentioned by Shepard in regards to Tali and Garrus, which are the only two team members to have full-time roles in every single game in the trilogy and have a substantial fanbase.
Shepard: You two have been with me longer than most. You believed in me when nobody else did. Thanks.
It's also made clear that Shepard considers both Liara and Joker to be this. Chakwas can also express such sentiments. Whether Ashley/Kaidan still counts is left up to the player.
Showing this with the entire surviving playable cast of the series is pretty much the point of the Citadel DLC.
Uncle Sam Wants You: Or at least Admiral Hackett wants you to "Join the Fight!" in various posters around the Citadel.
Under the Sea: The final stretch of the Leviathan DLC has you searching for the titular creature over 5000 fathoms underwater.
Unexpected Shmup Level: Some portions of the game have Shepard manning a turret to blast away at massive enemies, or acting as door gunner on a drop shuttle. Once even both at the same time.
Unexpected Successor: If he survived the events of "Bring Down The Sky" in the first game, Balak goes from being the leader of a small batarian terrorist group to the highest-ranking member of the Hegemony, due to the Reapers wiping out the entirety of the upper leadership on Khar'shan.
The Unfought: Since Mass Effect 2, Harbinger was built up as the Big Bad of the series, and is stated to be personally leading the Reaper attack on Earth. However, the closest you get to fighting him is him blasting you with a laser as you rush towards the relay to the Citadel.
Unique Enemy: The Legion Assassin enemy, which is encountered during "Priority: Cerberus Headquarters" if Legion was given to Cerberus in Mass Effect 2. You may also encounter Jack, converted into a Phantom during "Priority: Cerberus Headquarters" if you didn't help her at Grissom Academy; they will even use Jack's typical battle quotes when they attack you. Morinth is this to a lesser extent, as she is a named Banshee during "Priority: Earth" who is otherwise identical to a typical Banshee.
Unwinnable by Mistake: Playing a New Game+ can create this on Mars. Certain pistols, the Scorpion particularly, lack the DPS to kill Dr. Core during the Bullet Time segment at the very end of the mission. This can be averted, however, by switching weapons (preferably a rapid-fire one) as soon as you gain control of Shepard.
Unusually Uninteresting Sight: Occurs in the Citadel DLC mission. A salarian fish stall worker is in a freezer on a smoke break. A ruckus goes down and C-SEC locks down the area. The Illustrious Commander Shepard Him/Herself, who was turning heads in a swank sushi restaurant moments earlier, stumbles into the freezer, a little worse for wear due to the events going down, with a gun at the ready. And what all does he have to say? "Hey."
Upper-Class Twit: In the Citadel DLC at the Casino Fundraiser level, we finally get to meet the infamous Paris Hilton expy Aishwarya "Aish" Ashland, daughter of Jonah Ashland, energy mogul and co-founder of Eldfell-Ashland Energy. And her poor father who is drinking both for relief from the savaging of his business's facilities by the Reapers (all those wrecked fuel facilities around gas giants you read about in planet descriptors, "most of them are his") and from his daughter's "self-absorbed phase".
Use Your Head: Krogan player characters in multiplayer use head-butting as their "weak" melee attack, in place of the Pistol Whip or gun butt of non-krogan characters.
There's a reason why "weak" is in quotes: the krogan headbutt is among the fastest and strongest of the basic melee attacks. A properly speced krogan can one-shot enemy infantry just by headbutting them.
The Usual Adversaries: Cerberus. The Reapers are the main threat, and their Husks are the primary mooks you have to fight, but Cerberus hounds Shepard and the Normandy crew every Goddamn step of the way.
Vengeance Feels Empty: Javik the last Prothean and the Prothean avatar of vengeance can be pushed either towards this realization (in which case he despairs and plans to commit suicide after the war) or away from it (letting him start enjoying his life again).
The Very Definitely Final Dungeon: The end game essentially starts with the assault on the Cerberus HQ, but the final battle takes place on Earth, with the final confrontation being on the Citadel.
Krogan: Kill off Wrex in Mass Effect 1, delete Maelon's data in Mass Effect 2and then sabotage the genophage cure to effectively lead the krogan onto a path of self-destruction.
Hanar and Drell: If Kasumi is dead or not recruited in Mass Effect 2, and you choose to save Jondum Bau's life, then the Reapers will conquer Kahje. According to a later news report on the Citadel, there were no survivors.
Quarian: Support the Geth in the final mission on Rannoch. This leads to...
If you chose to betray Samara for Morinth in Mass Effect 2, you have to fight her as a Banshee in London, and miss out on a war asset.
Sending Legion to Cerberus instead of activating him makes him come back as a Geth Assassin (pretty much just a re-skinned Nemesis) in the Cerberus base raid. This also makes you unable to end the geth/quarian conflict without genocide.
If you chose not to support the salarian teams on Virmire back in the first game and thus did not save Captain Kirrahe, his replacement in this game lacks his willingness to trust or support Shepard, meaning that the salarian STG will not defy the dalatrass in order to help against the Reapers if the genophage is cured.
Not responding to the distress call at Grissom Academy allows Cerberus to capture Jack and convert her into a Phantom with indoctrination.
If Wrex leads the krogan and you sabotage the genophage cure, which can only be accomplished by killing the salarian operative with you, either Mordin or Wiiks, Wrex will discover the truth and pull krogan support from the war with the Reapers before forcing you into a confrontation that claims his life.
In the Leviathan DLC, you can sacrifice Ann Bryson to narrow down the location of your target (basically, you'll have to search fewer systems). She becomes a war asset if she lives.
Villain Protagonist: Averted for the most part. Renegade Shepard's snarky attitude has been toned down in this game, and he or she will now feel the emotional weight of his or her actions such as shooting Mordin.
Viral Marketing: Pre-release, twitter accounts called "The Cerberus Daily News" and "Alliance News Networks" posted little bits of information, such as comm buoys going out, along with the comments being filled with the various races commenting on it, such as a quarian disproving theories that the Migrant Fleet is attacking the batarian homeworld, or an Alliance soldier commenting on a sudden, massive influx of batarian refugees through the Exodus Cluster relay and how the human colony of Elysium is ready for anything that may happen.
Voodoo Shark: The Extended Cut attempts to resolve the question raised in the original endings of how your squad mates got onto the Normandy. This is explained by your party members getting injured and Shepard calling the Normandy in for an evac. This begs the question of how the Normandy was able to get down from orbit in a matter of seconds, why an evac would need the Normandy instead of one of shuttles already on Earth, and why Harbinger stops firing and just stares at the Normandy during the entire process instead of shooting it down.
Waiting Puzzle: The Citadel DLC adds an optional one. James Vega challenges Shepard to break his record of 182 pull-ups, and you are completely welcome to do so via a long, long series of interrupts, both paragon and renegade. As in, each interrupt window lasts at least two seconds, with the actual pull-up taking about one second. James occasionally comments on your progress as you keep at it. If you do make it past 182 pull-ups, all you get for your trouble is an additional cutscene with James complimenting Shepard.
Walking Spoiler: The Citadel DLC's Arc Villain: a disgruntled clone of Commander Shepard, working with a former Cerberus agent pretending to be the comic relief in order to steal Shep's identity and the Normandy.
Walking Transplant: A major plot point of the Citadel expansion. During Cerberus' project to revive the dead Shepard in Mass Effect 2, they cloned him/her in order to have a complete set of replacement organs for Shepard in case something went wrong. The clone was kept sedated, but around the same time the Normandy SR-2 hit the Collector base the clone was revived by and escaped with a disgruntled Cerberus employee, and is the expansion's Arc Villain.
War Is Hell: The game has near endless examples of the trauma the Reaper war has already inflicted going on in the background.
The game opens with Shepard stating that "Anyone Can Die" in a war, driven home by the little boy's shuttle being destroyed by a Reaper as it tries to flee, traumatizing Shepard.
A senile old woman on the Citadel who keeps trying to get in touch with her son, a soldier who "hasn't called in a while" because he is in an active war zone. The asari clerk she is talking to tries to remind her that they have already had this conversation many times, but the woman's senility not only makes her forget that she has already been told there is no news, but she also begins to incorporate the asari into the memories that she does have. Then the conversation repeats...
An asari commando who killed a crying girl to prevent her from giving away their position, and keeps begging for a gun so she can put a bullet in her own head. The crying girl may have very well been Joker's little sister.
A human soldier who was injured and whose wounds became infected, so despite receiving proper on-site medical care, still had to have his leg amputated afterwards.
One girl in the refugee camp stands patiently near a converted information kiosk, because her parents said they would meet her there, even though they were on different escape shuttles. The turian on duty knows full well that her parents are not going to make it, but cannot bring himself to tell her. She slowly works it out herself anyway, and resolves to wait for them all the same.
It is shown through the interaction with squad members as many of them get reports of their families being killed or worrying about news of that, homeworlds destroyed, etc. And the strain that it puts on Shepard is very noticeable.
Ashley's little sister was a newlywed... and her Alliance Marine husband was K.I.A. You can find her standing in front of the remembrance wall in the refugee camp even if Ash was not the Virmire Survivor.
Alternately, Kaidan, previously notable for his complete lack of parental issues, can tell you that his father has gone MIA and is presumed dead. Like Ashley's sister, the implication is that this happened regardless of which one made it off Virmire.
An elcor diplomat asks you to help in the evacuation of the elcor home planet, Dekuuna, which is under siege by the Reapers. After the rescue, Shepard will ask how many they saved, and the diplomat will simply answer, "Not. Enough." Elcor are known for the lack of emotion in their speech, since they communicate emotions through pheromones, and subtle facial expressions and tones at best, but this time he does not preface his speech with an emotional explanation, you can actually hear the grief in his voice, particularly in his hesitation to speak.
After the mission on Sur'Kesh, Liara's drone assistant, Glyph, reports that the colony world of Tyvor stopped reporting in. When pressed for details it unveils that the entire colony detonated their nuclear arms on themselves when the Reapers attacked.
The War Room: The Normandy comes with a very in-depth one that allows players to keep track of their war assets.
Weak, but Skilled: Any MP player who is using one of the starter classes and weapons to rack up high scores.
The Engineer gets one of these they can throw into position, and see through walls.
The Cerberus Engineers can deploy them as well; in a subversion they are quite powerful and tough to destroy.
Female Quarian and Geth Engineers can also use one in multiplayer. The Quarian one is offensive, the Geth one can restore some shields.
Weaponized Offspring: The Ravagers release tiny Swarmers when wounded, which crawl towards the attacker and try to push them into the Ravager's line of fire.
We Are Struggling Together: Despite the Reaper invasion, some of Shepard's potential allies are trying to kill each other. Shepard will need to resolve their issues to get their support.
Wham Episode: The Thessia mission. Not only does the homeworld of the galaxy's most prosperous species fall, it turns out that the asari owe their prosperity to Prothean technology that they have been hoarding to themselves, in blatant violation of their own laws against withholding such technology. For the first time in the whole series, Shepard flat-out fails thanks to Kai Leng's dirty tricks. It is very quiet on the Normandy afterwards. What makes this hit harder is that Shepard just came from a resounding victory on Rannoch, where s/he took down a Reaper Destroyer on foot.
The entire Leviathan DLC is one massiveWham Episode. Shepard finally discovers the true origins of the Reapers.
Admiral Hackett: Nothing's happening. The crucible's not firing.
During the mission to Sur'Kesh, Cerberus attacks the STG facility and both Mordin and Shepard's squad mention that Cerberus must have been helped by a mole in STG to get there that quick, but this is never brought up again later and whoever it was remains unrevealed.
The Raloi, who are mentioned in passing as a race that was only discovered 18 months previously. When the Reapers show up, they immediately throw their hands up, inform the Galaxy that the Reapers aren't their problem and they're going to destroy all their advanced tech so the Reapers hopefully won't see them as a threat. Their fate is unknown.
The pre-Extended Cut endings were this for the entire galaxy, which was what led to its creation in the first place. Even with the Extended Cut, Twitter posts from developers are the only source of information on the fate of the entire population of the Citadel, which is troubling considering the state it is in in the endgame and its outright destruction in two of the original endings. Not one single Citadel-bound NPC (that isn't a former squadmate of Shepard's) is mentioned or shown anywhere in the endgame or epilogues, and the ending slides added by the Extended Cut only reveal the fates of former squadmates. What happens to the current crew of the Normandy after they leave the planet they crashed/landed on is as much a mystery as the exact meaning of The Stinger.
The fate of every racial homeworld that isn't Earth, Tuchanka or Rannoch.
What the Hell Are You?: In Leviathan, the titular character has this reaction upon encountering Shepard, referring to them as "an anomaly" that has never manifested in any of the previous Cycles.
What the Hell, Hero?: No matter how you resolve the genophage situation, someone is going to chew you out for it:
If you cure the genophage, the salarian dalatrass emails you and explains that she will withhold Salarian Union suport from the Crucible since you have just doomed the galaxy to another Krogan Rebellion after the Reapers have been dealt with. However, depending on your actions in prior games, the rest of the salarians decide to support you, especially for saving the salarian councilor.
If you decide to sabotage the cure, Mordin catches on to what you are up to and expresses indignation that Shepard will throw all that work away for a backroom deal with the dalatrass. He can, however, be persuaded to come around to your viewpoint, depending on who is in charge of the krogan clans and who survived the mission so far.
If you sabotage the cure and you completed his family armor quest in the first game, Wrex rails at you for being two-faced when he confronts you on the Citadel.
What the Hell, Player?: A minor one in the casino infiltration mission in the Citadel DLC. An extraneous opportunity arises to rob an ATM. Upon doing so, you get 3000 credits... and +2 Renegade rep to remind you that you just robbed an ATM.
What You Are in the Dark: The salarian dalatrass offers the full aid of the Salarian Union in building the Crucible, provided you sabotage the genophage cure. She specifically points out that nobody will know what you did, as the countermeasures they have in place will initially make it look like the cure was successful, and when the continued presence of the genophage is discovered it will look like a good-faith error. Depending on which characters have survived this and past games, and which decisions you make here, your complicity can be discovered, leading to a severe criticism of Shepard.
The ending. Do you take the chance that people can manage their own future and destroy your enemy regardless of collateral damage? Do you give yourself absolute power and police the galaxy in place of your enemy? Do you take the chance that your enemy is right and rewrite the entire galaxy? Or do you reject all the other choices and leave everything to the next cycle for the sake of a moral point?
"Where Are They Now?" Epilogue: In the main three endings, the Extended Cut provides a slideshow that shows the state of various characters and worlds, unless you take Refusal, in which case an alien in the distant future relates how they used the information from this cycle to beat the Reapers for real, or do poorly enough that the Crucible backfires, in which case you just get a short, bleak narration from Hackett.
Whip It Good: The Cerberus defectors (or 'Phoenix troopers') who join the Alliance seem to have dual energy whips as their Weapon of Choice, incorporating them into almost all of their attacks. Oddly, these are nowhere to be seen on loyal Cerberus troops.
Not anymore - "Retaliation" introduces the Cerberus Dragoon, which is the finalized, mass-produced version of the Phoenix trooper. In addition to their iconic energy whips (which are gold instead of blue) they come equipped with Hornet submachine guns and heavy armor, but lack shields or barriers and the Phoenix troopers' more advanced biotic abilities, making the Phoenix something of a Super Prototype.
Whole Episode Flashback: The trilogy basically becomes this if you go with the Refusal ending. It ends with the hologram of Liara retelling the events of the war.
Liara: My name is Dr. Liara T'Soni. Herein lies the recounting of our war with the Reapers.
Wolverine Claws: The vorcha characters have Omniblade claws for their melee weapons.
Shepard and Liara/the Virmire Survivor, if you pursued a romance with them and then a different crewmember in the second game.
Potentially applies to Tali or Garrus, if you pursued one of them in the second game and choose to dump them in 3.
In the airlock while preparing to board the Geth Dreadnought, two characters, if they are rival LIs, may have an interesting conversation. If you haven't committed, for example, Ash and Tali will start getting testy with each other. If you have committed to Tali beforehand, however, the snipping starts, and then both realize it's a conversation direction neither wants to go down and they instead talk about anticipating the geth-killing spree they're about to partake in.
In the Omega DLC, this is the relationship between Aria and Nyreen.
Worth It: After the party in the CitadelDLC, several party members will wake up hung over (or with indigestion in the case of lactose-intolerant Kasumi who thought she was drinking soy) but claim that they are had a great time anyway.
If you romanced Tali in the second game, she says this after the Suicide Mission. When she returns to the Normandy, she repeats this in her first conversation:
Tali: And for the record? Still totally worth it.
Worthy Opponent: The Illusive Man, despite being one of the main antagonists of the game, has nothing but the utmost respect for Shepard and lets him/her know it multiple times throughout the game, always attempting to get him/her to see his point of view and join him, rather than just killing him/her. He also seems concerned that Kai Leng's lack of such respect for Shepard's capabilities may become a problem. It does.
Would Not Shoot a Civilian: The CAT6 mercenary group from the Citadel DLC is composed of soldiers dishonorably discharged from the Alliance, many of whom also have criminal records. However, after the sushi restaurant shootout in the first level, EDI notes that, according the news, "Civilian casualties seem to be restricted to... fish."
X-Ray Vision: Enemies are visible through walls with the geth's Hunter Mode. An equipment item added in the Reckoning DLC can allow any class to see through walls.
You Have Outlived Your Usefulness: After Cerberus began to really dig in to the technology left from the Collector base, the Illusive Man began having his scientists killed after they had finished their assignments. "Contract terminated" was the euphemism in use.
If you romanced the Virmire Survivor or Liara in the first game and someone else in Mass Effect 2, the infidelity will be addressed. This will also apply to any Mass Effect 2 love interests, except Jacob, if you did not romance anybody in the first game.
If you romanced Jacob in ME2, he is the one that cheated on you, as you will find out soon after you meet him.
Yo Momma: In his unedited un-submitted interview questions strewn about his (former) Citadel apartment, Anderson talks about how he broke the quiet tension amongst his squad of marines while in transit to combat during the First Contact War by using such a joke. Another marine responded in kind, and tension was averted.
Your Head Asplode: Headshots have become cathartically more interesting. Krogan characters can sometimes get the same result by headbutting people. Batarians can do so reliably with their Power Fists. Vorcha remove heads with their omni-claws.
Zombie Apocalypse: When not indoctrinating the people, the Reapers will mutate existing species into their footsoldiers. The previous games introduced husks and scions (human), Collectors (Protheans), and praetorians (human/prothean hybrids) but this game introduces cannibals (batarians with an Arm Cannonmade of a human), marauders (turians), ravagers (rachni), banshees (asari) and brutes (krogan/turian hybrids). Learning and controlling the process (in turn giving them control of Reaper forces, or so they hope) turns out to be Cerberus's primary goal.