This game has its own prequel, Episode Enyo, a short first-person Quake campaign following one of the game's antagonists.
Slave Zero X contains examples of:
- Advancing Boss of Doom: Uriel's prototype biomecha is so hideously powerful that even touching it will instantly kill Shou. Whenever it shows up on screen, you can't fight it directly, and have to run away as fast as possible instead.
- Arrogant Kung-Fu Guy:
- Flashbacks show that in the past, Shou was the best fighter in the Guardians, and he knew it. His attitude was part of the reason Kurikara passed him over in favor of Isamu for the assassination mission four years ago, with disastrous results. There's still a bit of this attitude about him in the present day, though it's not as prominent.
- Shou's Evil Counterpart among the Five Calamities, Atavaka, sees himself as perfect and everyone else as beneath him. Ironic, since he's a brainwashed Isamu.
- Art Evolution: Compared to the original game, the Slave designs in X have realistic proportions and look downright monstrous (which is what Ken Capelli originally envisioned when designing them).
- The Atoner:
- Kurikara has trained the Guardians to stand against and ultimately kill the SovKhan in order to atone for his past sins. He gets notably pissy at the end of the game when the SovKhan manages to escape with his life, because that means his atonement isn't done and he can't rest yet.
- Shou himself is ultimately revealed to be one of these as well. When the Guardians made an attempt to kill the SovKhan four years ago, Shou's arrogance and poor attitude led to him being passed over for the mission in favor of his lover Isamu, who was less skilled, but more disciplined. A combination of wounded ego and concern for Isamu's safety led to Shou lashing out, and the two men parted on bad terms; Isamu was then captured during the mission and brainwashed, becoming Atavaka of the Five Calamities. Shou's ultimate reason for stealing X and taking on the SovKhan's entire army by himself was to make up for these past failings.
- Attack of the 50-Foot Whatever: Instead of fighting Shou and X himself, the Regent activates an incomplete prototype giant Slave and sics it on them. It doesn't work out for him as it crushes him to death as it's dying.
- Background Boss: The giant Slave prototype the regent unleashes on Shou, as well as the SovKhan's final form.
- BFS: Shou and X's preferred weapon. It's unclear whether it's a man-made sword or if X produced it.
- Bio-Armor: Slaves in general. X is unique in that she's a self-aware individual with thoughts and feelings of her own. This becomes a sticking point between her and Shou, her pilot, the guy wearing and controlling her, later in their story.
- Bio Punk: The original game had a touch of this, what with the giant biological mecha and all, but it's in full force in X, where the Slave Unit you're in is a monstrous suit of Bio-Armor a la Guyver, Megacity has a grotesque H. R. Giger skyline, and Organic Technology and Organic-shaped technology are the rule of the day.
- Blue-and-Orange Morality: X is a rare protagonist example. She wants the same thing Shou does: the SovKhan and anyone working for him brutally slaughtered. Except Shou wants that for pretty understandable reasons: Because the SovKhan is a brutal tyrant and brainwashed Shou's lover Isamu into becoming his right hand man. X wants the same, but less for any "moral" reasons and more because SovKhan declared her defective, and she took personal offence to that statement. Her reasons for fighting slowly start to align with her wearer's as the game goes on.
- Bloodier and Gorier: Compared to the original game, X throws buckets of High-Pressure Blood and Gorn with each and every onscreen kill.
- Bury Your Gays: Isamu, having been brainwashed and transformed into Atavaka, is put down by his lover, Shou. Shou himself is also critically injured at the end of the game, leaving it up in the air if he survived long after he and X escaped.
- Control Freak: In his efforts to turn the Guardians into the ultimate anti-SovKhan resistance force, Kurikara controls essentially every aspect of their lives, granting them effectively zero agency. This is Shou's main point of conflict with the man and the cause for much of his rebellious behavior.
- Crapsack World: Now that we're out of a giant living mecha and on a human scale, we can see what the Megacity is actually like. Yeah, it's not a great place to live. The city is riddled with pollution and poverty, the Sovereign Khan rules with an iron and flesh fist, police brutality is standard policy, and that's before we get into the biological horrors within. As an example: Not only are civilians encouraged to spy on their fellows and report anything that might be seen as dissent, the city offers a cash reward for it.
- Cyber Ninja: Shou is a Bio Punk take on this trope. Imagine if Raiden was in a Guyver suit. A fully sentient Guyver suit that talks to him and slowly learns from being attached to him.
- Cycle of Hurting: There is no Mercy Invincibility in this game — unless a character's ass is flat on the ground, they can be hit, and each hit stuns Shou and most normal enemies for a brief moment. While this means you can often stun-lock large quantities of enemies at a time and whale on them until they explode, it also means that if you're standing in a big crowd of enemies and you get hit even once, you can expect to get hit dozens more times, as they all start attacking just out of sync with each other and stretch the stun duration out longer and longer.
- Dragon with an Agenda: Enyo, second of the Five Calamities, is less working for the SovKhan and more working against Shou. She outright states that she's planning to kill the SovKhan, and the only reason her and Shou aren't working together on this is that Enyo wants to be the one to do the deed, and is trying to kill the competition (RE: Shou and X).
- Eagleland: General Hercules J. Thorman is a textbook example of 'Murica the Boorish who thinks he's representing America the Beautiful. Thorman is a Large Ham General Ripper who wears an American flag for a cape and blows a lot of hot air about "liberty," "justice" and "freedom" while serving as one of the top enforcers of a fascist police state. He also seems to have a rather skewed idea of what America actually was; while his statements about the glory days of "the American Empire" might be true in the context of the setting, his belief that he's descended from a long line of mighty American warriors known as "quarterbacks" probably isn't. Further emphasizing his hypocrisy, the end of his boss battle reveals that 1) inside his mechanized muscle-suit, Thorman is actually a shriveled, decrepit old man; and 2) he's also a Dirty Coward, frantically offering to abandon the ideals he'd so vocally defended and sell out his former comrades in exchange for Shou sparing his life. Shou is understandably not interested and swiftly decapitates him.
- Fighting Your Friend: Atavaka is a brainwashed Isamu, the man Shou loves. Their final duel to the death is appropriately tragic.
- Foregone Conclusion: Slave Zero X being a prequel to Slave Zero, Shou and X's assassination of the SovKhan is bound to fail, arranging events leading to Ch'an's eventual battle with and subsequent victory over the SovKhan in Slave Zero.
- Genre Shift: In gameplay at least. The original game is a Third-Person Shooter Mecha Game, while the prequel is a 2½D Beat 'em Up with Hack and Slash elements.
- Good Is Not Nice: Kurikara, the leader of the Guardians and Shou's master; Yes, he also wants the SovKhan dead, but he is fuming that Shou is going rogue on a one-man-murder crusade through the Megacity. Once he realizes in the second part that Shou isn't going to stop until he or the SovKhan is dead, he hooks him and X up with Ayesha and goes silent. Until the Regent is killed, on which he gives Shou his formal blessing to wreck the Sovereign Khan's ass. And then he slips right back into his old self at the end, when Shou/X simply leaves the Megacity with a Slave Zero embryo, and the SovKhan's whereabouts unknown.
- The Goomba: Ordinary human security guards armed with maces are the weakest of the SovKhan's soldiers, going down in just a single hit. In contrast, ordinary human security guards armed with guns are actually capable of taking multiple hits before dying.
- Grand Theft Me: In the leadup to the battle with the Regent, X eventually gets sick of Shou ordering her around and forcibly hijacks his body. It takes a Battle in the Center of the Mind and some character development on Shou's part before they're able to work together effectively again.
- Gun Nut: Enyo, to a fetishistic degree. One of the SovKhan's Five Calamities, "Beloved by the Bullet," she's single-mindedly obsessed with guns, bullets, killing, and killing people with bullets shot from guns.
- Hopeless Boss Fight: Atavaka is ridiculously overpowered during his first boss fight with Shou, and you're not supposed to be able to beat him. If you manage to do so anyway, he gets right back up and performs a finishing move on you so the plot can move on like it's supposed to.
- Irony: Enyo, "Beloved by the Bullet," is defeated when one of her guns jams, giving Shou an opening to cut her down. Shou lampshades this in his Post-Mortem One-Liner.Enyo: It... jammed...
Shou: Hmm... is that so? Not so beloved, then. - Kent Brockman News: Channel 9 "The Truth", a SovKhan sponsored news channel that can be heard throughout the game. It comments on Shou's rampage through the city, and 95% of what it says is complete bullshit. And it isn't even a real person on the anchor, it's just the Regent putting on another voice as part of his job.
- Long-Haired Pretty Boy: Outside the X Bio-Armor, Shou is a very pretty man, with delicate facial features and long, flowing hair. His lover Isamu qualifies as well.
- Ludicrous Gibs: If you damage an enemy just enough to defeat them, they will turn dark and then melt away shortly after hitting the floor. If, however, you're able to keep hitting them after you've defeated them or you overkill them with a powerful enough attack, they will instead explode into chunks of bloody meat.
- Manipulative Bastard: Every word out of the Regent's mouth(s) is calculated to instill doubt, confusion, and internal conflict in Shou and X, and he does a pretty good job of it, even though the pair know that's exactly what he's doing. He's also the one who's responsible for shaping the relatively sweet-natured Uriel into a fanatical SovKhan loyalist, and seems to be in charge of the SovKhan's propaganda in general since apparently he's the one who provides the voice of the Channel 9 news anchorwoman, so being a Manipulative Bastard is essentially his job.
- Meat Moss: Starts becoming relevant halfway through the game, particularly in the Heart, where flesh is spilling out of labs, and in the last legs of the game, which is a temple dedicated to SovKhan. Rather worryingly, it doesn't seem to be a sign that things are going horribly wrong (at least from the SovKhan's perspective): There are still scientists working in the Heart even while lab experiments run amok, and the temple priests are still worshipping in the pits of biological slurry. The meat growing everywhere isn't a unintended problem, it means things are working as intended.
- Multiple Head Case: The Regent has multiple different mask-like heads sitting atop his shoulders, and regularly switches which head he's speaking from. While each head probably doesn't have its own actual personality, he does take on a different voice and persona for each one as part of his manipulation tactics.
- Not Drawn to Scale: In the original game, the Slaves are a 2-story tall beings and the cars and tanks look like toys to them. The Slaves here are only larger than humans (just compare the height of an average human security guard to a Slave next to him). This is because the Slaves currently present are from an earlier, smaller line of Slaves. The SovKhan's forces developing the giant Slaves of Zero is a critical plot point.
- One-Winged Angel: For the final phase of the SovKhan's boss fight, he turns into this giant biomechanical thing with six arms and a Belly Mouth, which attacks you from the background of the surreal alternate dimension he's transported you to.
- Out-of-Character Alert:
- After defeating Uriel, Shou contacts Ayesha and regretfully informs her that her beloved drone sacrificed itself to get him crucial information. Ayesha, eerily chipper, replies that everyone who gets close to Shou inevitably dies. This gives Shou a few seconds of warning that the Regent has located and captured Ayesha and hijacked his comms, and things are about to get a lot worse for him and X.
- During Shou's final approach to the Regent, the latter imitates Kurikara's voice and pretends that the Guardians are being cut down by the SovKhan's forces, lamenting that they trusted Shou and that he let them all down. Shou immediately sees through the ruse, pointing out that Kurikara has never trusted or had any amount of faith in him and would never say such a thing. (As it happens, Kurikara has developed enough faith in Shou to at least capitalize on his actions and send the Guardians into battle behind him, but Shou has no way of knowing that at the time.)
- Phlebotinum Dependence: Uriel of the Five Calamities has been fused with a prototype biomecha that is hideously powerful, but also hideously unstable — requiring a constant infusion of dark matter just to keep from falling apart. Defeating him involves finding and destroying the dark matter infusers located throughout the level while avoiding contact with Uriel himself.
- Playful Hacker: Ayesha, a plucky Techno Wizard from the megacity's lower levels who's fighting against the SovKhan's regime in her own way. Although she's explicitly not a Guardian, Kurikara taps her to serve as Shou's Mission Control once it becomes clear Shou has no intention of stopping his one-man murder crusade.
- Police Brutality: Oh, my dear, yes! One of the first scenes in the game is a pair of officers shaking down and murdering some unfortunate for drugs so they can take the drugs themselves. Note that one of these officers is wearing a Slave.
- Pre-Asskicking One-Liner: An example from the demo:"Pathetic, I'll wear your skin for my next promotion!" [cue boss fight]
- Run or Die: Both of Uriel's encounters: Either get the hell away from him, or get crushed underneath.
- Token Good Teammate: Among the Five Calamities, Uriel is the only one who harbors no real animosity towards Shou, actually trying to talk him down before their encounter and forgiving him when Shou makes it clear he won't stop. He also genuinely considers the other Calamities his friends and truly believes the SovKhan to be an infallibly virtuous messiah. Between his generally sweet nature, how obviously he's been manipulated to bring him to his current mindset, and the horrific transformation that's been inflicted on him by fusing him with his biomecha, he comes across as a Tragic Villain whose ultimate defeat is practically a Mercy Kill. Had circumstances been different, he and Shou probably would have become friends.
- Tragic Villain:
- Uriel has "The Hero of Man" for his title among the Five Calamities, and it's not entirely ironic — his dialogue portrays him as a genuinely kind, thoughtful, and heroic soul who wishes no harm on anyone and truly views the other Calamities as his friends. Unfortunately, the Regent's manipulations have convinced Uriel that the SovKhan is benevolent and infallible, and that Uriel is his chosen champion. Because of this, Uriel has allowed himself to be fused with a prototype biomecha that should be an unstoppable engine of destruction... but unfortunately, it's so incredibly unstable that it requires a constant supply of dark matter just to maintain its structural integrity, leading to Uriel being sealed away inside the Heart. Shou's killing of Thorman and Enyo, and his ultimate goal to kill the SovKhan, eventually convinces Uriel that Shou is irredeemably evil, and while Shou doesn't seem to regret putting Uriel down in the end, he doesn't take any pleasure in it either.
- Atavaka is Shou's lover Isamu, captured and brainwashed during the Guardians' attempt to assassinate the SovKhan four years before the start of the game. Unfortunately, he's so far gone, and so strong and skilled, that having an "I Know You're in There Somewhere" Fight isn't an option — Shou has to go all-out fighting Atavaka, or he will definitely die. Shou manages to defeat Atavaka, and the old Isamu seems to re-emerge in his final moments, but even then he tells Shou to let him go for the good of the future. After one last Anguished Declaration of Love, Shou impales Atavaka through the chest, killing Isamu for good.
- Traintop Battle: One stage is set atop a subway train going through the city.
- Transhuman Abomination: Where to begin?
- Inside the Heart, the lab complex/power plant of Megacity S1-9, we see the bulk of the Megacity's genetic experiments: warped, mutated humans that have "corrupted divinity" forced into them, resulting in things like giant crawling heads with halos, a human with a massive third arm growing out of its shoulder, a weeping humanoid that can summon hands from surfaces, and what can best be described as a amniotic sac full of worms on legs. Worse, this isn't even on accident: aside from them getting loose and running rampant through the labs, this is implied to be the intended results, and once the SovKhan's forces get a handle on them, they're fielded just like the rest of his army.
- And then there's Uriel. Uriel has been fused with a Slave Unit and pumped full of Dark Matter, creating a ginormous biomechanical centaur thing. He's so powerful that simply touching him is enough to instantly kill Shou.
- Finally, there's the SovKhan himself, who adopts a truly massive and monstrous form in the final phase of his battle with Shou.
- Uncertain Doom: After fighting their way through the SovKhan's forces inside his fortress and defeating him, Shou and X have potentially permanently fused their minds and suffered critical injuries. Though they manage to capture the last of the Zero Slave embryos and make their escape, the game ends before we can learn of their fate.
- Ungrateful Bastard: At the end of the game, after the fused X-Shou has literally beaten the divinity out of the SovKhan, the greatly-diminished tyrant loses all composure and teleports away in a panic. Kurikara demands that X-Shou go after him and finish the job. X-Shou, who is critically injured, standing in a collapsing palace, and has no idea where the SovKhan went, understandably goes "fuck that" and gets out instead. Despite Ch'an pointing out that X-Shou has struck a massive blow against the SovKhan and his regime and turned the tide in the Guardians' favor, and despite X-Shou showing up shortly afterward with the last Slave Zero embryo (setting up the events of the original game), Kurikara continues to whine about how the SovKhan still lives, his Chosen One has failed again, and his atonement is still out of reach.
- Walking Armory: Enyo has a lot of guns. Hidden somewhere on her person are a Sniper Rifle, a pair of SMGs, a shotgun, and a Hand Cannon.
- Xenomorph Xerox: X has a decidedly xenomorph-like facial structure, with no visible eyes, a mouth set in a permanent, lipless grin, and an extended cranium (in this case a pair of demon-like horns rather than the usual lengthened skull). She also has a biomechanical appearance, insane agility, and a tendency to violently murder anyone who comes within a hundred feet of her.
