The game is set in the far future of 2320. Mankind has colonized the Solar System, including Callisto, the icy moon of Jupiter. Nicknamed "The Dead Moon", Callisto is home to the feared Black Iron prison colony, owned and operated by the United Jupiter Company. The player character, Jacob Lee, is a cargo flier turned prisoner against his will held at the facility, but his stay is interrupted when the other inmates suddenly begin mutating into homicidal monsters. Using a combination of firearms and melee combat, Jacob must fight for survival while uncovering the dark secrets that lie within Black Iron's depths.
The official cinematic trailer can be found here
. The Schofield Cut trailer can be found here, while the gameplay trailer can be found here.
On June 28, 2023, a new story campaign DLC, Final Transmission, was released which concludes the game's story.
Tropes that apply to The Callisto Protocol:
- Abandoned Area: Almost every area on Callisto becomes this due to the infestation spreading across the moon. The best example would be Arcas, the original colony constructed beneath Callisto's surface. By the time Jacob arrives, it's become a Ghost City, having been abandoned and left to rot for seventy-five years and is in a sorry state of disrepair.
- Another good example would be the main prison complex. When Jacob first makes his way through it, the facility has collapsed into total anarchy as the Biophage run rampant and a majority of the prisoners and personnel struggle to survive. When Jacob returns to it only several hours later, the place is deathly silent and completely devoid of any life.
- Adaptive Ability: The main strength of the Biophages and the reason why the UJC is so interested in them is because of their ability to rapidly evolve in a short amount of time. However, in the actual gameplay, while the Biophages can evolve mid combat, all this really does is refresh their health and increase their damage, with no real change to their behavior or attack patterns.
- Air-Vent Passageway: Black Iron Prison (and, eventually, the Arcas Colony) has plenty of airvents Jacob can sneak through, with at least one passageway expressly being set up as Schmuck Bait by the guards (i.e. the vent is behind a rolling grinder that moves back-and-forth along a narrow passageway) in order to prevent inmates from escaping.
- Ancient Conspiracy: Dr. Mahler reveals that the Black Iron Prison warden belongs to a secret group that has been looking for ways to advance human evolution for centuries, and the outbreak in the prison was wholly orchestrated by them to search for someone compatible with the infection.
- Anti-Frustration Features: Similar to Dead Space, the ammo that you find is based on which weapon you're using the most, so you'll always have a decent amount of ammo for whatever your preferred gun is. However, the amount of ammo you get is low enough that you still need to rely on the melee combat system for most of the game, only using your firearm as a finisher or the last hit in a combo. Note that what the game actually does is prioritize spawning any ammo which you have less than 2 stacks of in your inventory. This can become a frustration feature if you keep selling off ammo for a weapon you don't use and the game keeps giving you more of it instead of ammo for the gun you do like. It also means you shouldn't purchase any guns you don't plan to use, even though they don't take up inventory space themselves, as owning a gun will start spawning ammo for it.
- Stealth killing one of the Blind doesn't alert any of its nearby friends, no matter how much noise such a kill seems to make. Ditto for grabbing one and throwing it into a spike wall. It makes clearing a group of the things much easier than it would be if they actually reacted to all the noise made during a kill.
- Asshole Victim: Why the Ancient Conspiracy created Black Iron in the first place. They believe the alien beast's larvae are necessary to forcibly evolving humanity into their 'next stage', capable of surviving the hostile conditions of deep space, just like it could. They had some hope with 'Subject Zero', an infected from a prior outbreak who proved capable of retaining his intelligence and even controlling other mutants through the infection, but he was killed by security forces before they could detain him. Their efforts to replicate his condition requires multiple test subjects to identify what allowed him to reap the benefits of the mutation, to which end they created a prison atop the old outbreak site and regularly turn the inmates into monsters to try and control the transformation, using victims nobody will greatly miss for their experiments. Given that Jacob stumbles across a room where some untransformed inmates brutally tortured and slaughtered some guards and hung their bodies from the ceiling, with a recording from one of them revealing it was just for fun, it's hard to argue some of the infected don't deserve their fate. On top of that, considering Jacob was tossed into the prison and tortured for a crime he didn't commit it's hard not to say the guards and staff were any better.
- Attack Its Weak Point:
- A mass of tentacles will emerge from a Biophage when it's about to mutate. Shooting the tentacles before it can transform results in an instant kill on the Biophage.
- The armored security robots can be damaged and eventually defeated by shooting their glowing red eye. It still takes a lot of shots and they can kill you instantly if you screw up, so it's way more effective just to stealth around them.
- Ax-Crazy: Several of the prisoners Jacob comes across are completely nuts. Hell, before he even encounters a Biophage, his first two kills are two inmates who are clearly unhinged and are beating the crap out of a third, relishing in the pain they've caused as they try to murder Jacob as well.
- Elias points out that a lot of the prisoners in solitary confinement are batshit insane. Considering Jacob later finds a room with a lot of dead guards strung up, he's most likely right.
- Berserk Button: The Blind Biophages are usually only triggered if you jog or run too close to them; they won't even respond to melee combat as long as you're not right next to them. Fire a gun, however, and every Blind in the area will swarm you, more often than not leading to an impossible fight. This means if you do get into a fight in a Blind-infested area, you can't use your firearms or else bring the entire area down on you.
- Bishōnen Line: The ultimate intent of the eponymous 'Callisto Protocol'. During a prior outbreak, one infected managed to retain their humanity and intelligence despite the infection, able to reap its benefits of enhanced strength and durability without any of the side-effects, and even able to control other mutants through the infection. This 'Subject Zero' was killed whilst containing the outbreak, but his existence convinced several high-ranking members of the UJC that the Biophage larvae were the key to unlocking the next stage of human evolution, granting them bodies capable of surviving the intense conditions of deep space. Attempts to artificially replicate his freak mutation in the Black Iron prison and lab complexes on Callisto proved unsuccessful, so Warden Cole deliberately causes another biophage outbreak, believing that a similar chaotic and uncontrolled situation will result in the same mutation amongst one of the infected. He initially seems to be proven correct with Captain Ferris, who manages to retain his intelligence and roughly humanoid body shape, but when pitted against Jacob in a fight to the death, the damage Jacob inflicts upon him eventually sparks a more volatile mutation into a more monstrous form, which Cole attributes to Ferris being an 'imperfect vessel'.
- Bittersweet Ending: The Final Transmission DLC reveals that Jacob failed to fight through his Bolivian Army Ending in the main campaign and was torn apart by the infected. However, Mahler manages to use his CORE's still active connection to Dani's to transmit all her evidence against Cole and Kallipolis, ensuring that they won't be able to sweep what they've done under the rug. Mahler accepts her imminent death as Black Iron finally self-destructs, while Jacob dies believing he escaped Callisto.
- Body Horror: The game is a spiritual successor to Dead Space, so twisted mockeries of the human form are only to be expected. Standout examples from the trailers include towering giants with grotesquely distended jaws full of needle-sharp fangs, elongated tentacles with human heads on the end, quadrupedal monsters that appear to be made out of multiple bodies that have been fused together, and much more.
- Bolivian Army Ending: While Dani manages to successfully escape Callisto with all the evidence she needs to expose the UJC's wrongdoing, Jacob decides to stay behind in the prison so that Dani can take the last escape pod and begins fighting off endless waves of infected while the entire prison is set to self destruct. The one thing that is keeping this from going more downer is Dr. Mahler contacting Jacob regarding a possible way out and temporarily shutting down the self-destruct, just before Captain Ferris (who's probably a hallucination, given that he's already Deader than Dead) lunges at the camera. With the Final Transmission DLC, this trope no longer applies.
- Boom, Headshot!: Averted; not only do headshots not seem to do noticeably extra damage, but Biophages can often keep fighting after having their head blown off anyway. Decapitating an enemy also makes it much more likely they're going to start mutating.
- The Conscience: Jacob's co-pilot Max has far more scruples and hang-ups about their job running supplies for the UJC than Jacob, constantly needling him about knowing there's something happening with the increasing terrorist attacks throughout the sector, whilst Jacob considers the pay check to be worth just ignoring anything odd and keeping their heads down. After his death in the initial crash-landing, Max's mutilated body becomes literally symbolic of Jacob's guilty conscience, appearing as vivid hallucinations from the new CORE implant interfacing with his brain whenever Jacob is subconsciously thinking about why he was imprisoned, aware on some level that it had something to do with the smuggled cargo kept underneath the medical supplies they were officially transporting that the pair stumbled onto. This is most noticeably shown when Dani drives them both back to the crashed CHARON and finds the supply box, Max's body appearing behind her in a Jump Scare when Jacob denies any involvement with the outbreak in Europa.
- Continuous Decompression: Several times Jacob experiences such events where the air should have run out long before managing to crawl to a door or losing his grip and being blown away.
- A specially egregious example is when Captain Ferris suddenly opens the airlock to the exterior of Callipso which, as was shown at the beginning, has a partially breathable atmosphere. The room is tiny and the pressure differential should also be rather small, but the game still vents Jacob as if he had been exposed to the vacuum of space.
- Contractual Boss Immunity: The two-headed Mini-Boss enemy type is immune to being grabbed by your GRP glove for no particular reason, so you can't insta-kill it by throwing it into spikes or off ledges.
- Contrived Coincidence:
- Lampshaded by Captain Ferris, who notes how strange it is that Jacob arrives just before the outbreak commenced throughout the prison, and how odd it was the Warden Cole wanted him captured alive and interred inside, accusing Jacob of being complicit in the chaos that's erupting around them. He turns out to be Right for the Wrong Reasons. Jacob doesn't have any direct involvement with the Black Iron outbreak, as Cole was already planning to unleash the Biophages to create an 'Alpha' in the chaotic situation, but it's implied that he was waiting until Jacob's arrival to start his experiment, so as to silence him due to his involvement in smuggling the Biophage Larvae to Europa, something Jacob wasn't 'officially' aware of, but did know he was secretly smuggling cargo underneath the medical supplies. Failing that, the fact that a known terrorist group raided a cargo ship containing evidence of Cole's involvement with the Europa attack would be a catalyst to Cole speeding up his timetable and unleashing the outbreak both as a way to start his experiment and tie up all loose ends in one go.
- A straighter example would be Dani Nakumura turning out to be the hacker that Elias locates within the prison needed to summon a ship from orbit for them to escape with. On the other hand, Dani's skills as a hacker were the primary means by which she was investigating the Europa outbreak she was framed as a terrorist for, and her same investigation into the classified truth behind that had her designated a top-priority threat to the UJC, resulting in Cole assigning her to the maximum security wing to keep her isolated, which ironically protected her from the initial outbreak.
- The only other prisoner Jacob meets (barring the two that try to kill him) is the Crazy-Prepared Elias Porter, who just so happens to have been imprisoned at Black Iron for decades and therefore knows the layout of the facility very well and has special privileges that will allow him to easily navigate it. It's only because of them meeting the moment Jacob steps out of his cell that he initially makes it as far as he does. However, with the reveal that Warden Cole has been monitoring Jacob's progress to see if he's the ultimate specimen, it's likely he knew about Elias and purposefully placed Jacob in the cell above his so they would definitely meet when the outbreak occurred, and Jacob would have a better chance at staying alive.
- Crazy-Prepared: Elias spent years mapping out parts of the prison and putting plans into place to escape in the event of a significant event that compromised the prison, with him conscripting Jacob into the plan the moment the latter escapes from his cell. Elias' uploading of codes into Jacob's CORE device allows him to access memories Elias uploaded months (if not years) earlier where he explains his objectives out loud while he's on work duty at the prison.
- Death World: From what we see of Callisto itself, the Dead Moon’s surface is so cold that anyone venturing outside is required to wear an environmental exosuit just so they don’t freeze to death on the spot. A hazard emphasised by the still-standing, snap-frozen inmates out in the snow, forever posed by their last moments. The only safety from the elements is the Black Iron Prison itself, which is little better considering that it’s fallen to the Biophage plague by the events of the game.
- Diegetic Interface: Similar to Dead Space, HUD elements are presented as existing in the game world rather than as an overt video game HUD. Your health is displayed on a tracking implant attached to the back of Jacob's neck, and weapon ammo and other information is shown as a hologram projected in front of Jacob from his suit.
- Dug Too Deep: The source of the original outbreak was a whale-sized aquatic monster that broke through when the original Callisto colonists drilled down deep enough into the ice to breach into the moon's subsurface ocean. The creature's larvae burrow into living hosts and induce uncontrolled accelerated evolution, creating mindlessly violent meat monsters. The secret society the Warden belongs to has been using these larvae to start outbreaks on Europa and Black Iron in the hopes of creating the next stage in human evolution.
- Dying Dream: In Final Transmission it's revealed that Jacob was torn to pieces fighting the Biophage horde at the end of the main game, and the whole DLC (including the Ferris jumpscare at the end of the main game) is a dying hallucination of Jacob's as Mahler extracts his memories via his CORE implant from his dying brain and torso and transmits them into space as a final testimony against Kallipolis and Cole.
- Early Game Hell: Once you're out of the tutorial and into the game proper, Jacob just has his prisoner jumpsuit, a stun baton, and his implant to his name. The GRP, better guns and even a more protective attire have to be found over the course of the game, all of which lend to better odds of survival because even the most basic of infected enemies can kill Jacob in a couple blows while they take a huge beating with your baton to bring down.
- Evilutionary Biologist: The secret society/cult that Warden Cole belongs to are revealed to have been experimenting on the biophage virus for this purpose: to create a new version of humanity that can survive extremely harsh environments, even space. In a way they succeed; biophages apparently can easily survive the extreme cold of Callisto's surface, and if you tilt your head, the One-Winged Angel form of Ferris has a twisted resemblance to an EVA suit.
- Finishing Stomp: Like in Dead Space, Jacob can brutally stomp on an enemy corpse, but this time to loot valuable items. If Jacob is melee killed by the Black Iron Security robots, they will curbstomp his head into red paste after dismembering one of his legs and throwing him on the floor.
- Foreshadowing: When Dani drives her and Jacob back to the crashed wreak of the CHARON to find the cargo the Outer Way were looking for during their initial boarding, she's shocked when it turns out to be just ordinary medical supplies, having suspected Jacob and Max from their supply runs to Europa prior to its outbreak, and believing they were knowingly transporting something dangerous instead. Jacob denies any involvement in the outbreak, noting that there were several other ships that were doing supply runs for the UJC at the time, only to get a Jump Scare from a hallucination of Max's mangled body glowering at him, a side-effect from his CORE implant newly interfacing with his head. When finding the alien beast's corpse in Arcus, Max finds a similar medical crate nearby the body and unprompted, opens up a secret compartment underneath the supplies, revealing containers of sealed test tubes that carry the creature's larvae. Towards the end of the game, the apparition forces Jacob to remember that he and Max actually found out about the secret compartment underneath their official cargo, but Jacob declined against investigating any further as to what they were really transporting thanks to the generous pay. Similarly, the apparition constantly appears and haunts Jacob during times whenever he is subconsciously thinking about the reason he was interred at Black Iron, as a manifestation of his guilty conscience, with Jacob actively suppressing his memories of his unwitting culpability in the horror going on around him.
- Gorn: The game starts out with Jacob and his copilot Max being forced to crash-land on Callisto, then shows us a lovely close-up of Max's half-gone face as he dies. It doesn't let up from there, with the monster designs showing off a lot of gruesome detail, and every death at their hands being excessively brutal.
- Ink-Suit Actor: The characters are modeled after their voice actors, most prominently Josh Duhamel as protagonist Jacob Lee, Karen Fukuhara as Dani Nakamura, and Sam Witwer as Jacob's nemesis Captain Ferris.
- Ironic Echo: In the beginning of the game Jacob cries out "I don't belong here!" when he is about to be put in Black Iron as a prisoner. In the ending, he says "I do belong here" to Dani as he sends her escape pod away, resolved to stay on the self-destructing Black Iron as his atonement for his part in the biophage outbreak on Europa.
- It Can Think: On several occasions Biophage will hide in plain sight and wait to ambush you. This is best seen outside on the freezing surface of Callisto, where they will stand perfectly still to blend in with the snap-frozen corpses of human prisoners and wait for you to get in close before attacking. This display of predatory cunning makes them out to not be as mindless as one would initially believe.
- Justified Tutorial: The opening sequence follows Jacob as he travels through the Charon to check on an emergency light and ensure that their cargo hasn't been damaged, utilizing basic movement and obstacle controls. The following sequence requires Jacob to sneak back up to the cockpit after it's boarded by members of the Outer Way.
- Killer Robot: Black Iron's human security force (which seems to consist of about 55 or so guards) is supplemented by a number of 8-foot tall humanoid robots with bulky jet black armored bodies and Cyber Cyclops heads. When the outbreak starts, the robots seem to be given orders to kill any escaping prisoners, as early on Jacob sees them gunning down prisoners and has to stealth around them. Even later on after Jacob gets better tooled up, the robots continue to serve as Nigh-Invulnerable enemies that Jacob is expected to stealth around instead of confronting directly.
- Made of Iron:
- The mutated prisoners appear to be pretty hard to take down, able to keep going even after losing a limb or two. Or even a head. Captain Ferris as the Alpha is practically Nigh-Invulnerable, being Immune to Bullets and capable of interrupting Jabob's close-range combos while barely getting staggered by multiple hits from his Stun Baton. His One-Winged Angel form is capable of getting damaged, but still takes far more hits than anything else in the game, having a regenerating Meat Moss shield covering his head that Jacob needs to blast through to damage him. And even after the Final Boss fight, he's still not done, reviving for a last-second Jump Scare on Jacob right as the game ends.
- Some of the strongest among the regular Biophage have to be the Blinded. While during stealth they can be finished off with a very simple takedown, if alerted they will prove incredibly difficult to kill, taking an insane amount of punishment before going down. And if they they manage to mutate, they become even worse.
- The Black Iron security robots, both literally and figuratively. They're mechanical, hulking killers that are incredibly strong and can kill you instantly, so during any encounter with one stealth is always encouraged. However, they do have a weakness, this being the red optic lens in the middle of their heads. Shooting it enough times will cause the robot to shut down.
- Made of Plasticine: Just like in "Dead Space", while enemies can take a lot of punishment before going down, it takes surprisingly little force to hack them apart. Your stun baton in particular turns out to be surprisingly effective at amputating limbs despite being, ostensibly, a less-than-lethal blunt weapon.
- Mad Lib Thriller Title: Though it makes sense given the Title Drop mentioned below, the game's title ficts the trope perfectly.
- The Many Deaths of You:
- Obviously taking a page or three out of Dead Space, expect a lot of nightmarish and gruesome death animations if you hit a certain hazard or fail to escape. Most here have Biophage aim for your head; either Jacob's head is crushed, torn off, eaten, or infected from the inside out. Lost an arm or a leg? You Are Already Dead!
- The "Contagion Bundle" DLC even markets 13 new death animations for Jacob as a selling point
- Meat-Sack Robot: The new main antagonist enemy in the Final Transmission DLC is the Biobot, a Security Robot which has had a number of its mechanical systems replaced with organic components, seemingly Biophaged ones. Due to its organic components, it's not Immune to Bullets like the regular robots are, but it still has several times the amount of health regular Biophage monsters have. Audio logs reveal it was an attempt by Dr. Mahler to create a controllable Biophage host, as an alternative to Warden Cole's Subject Alpha project. They're tough enough that Jacob breaks his stun baton hitting a barely functional prototype one. The first two you encounter are treated like Mini-Boss encounters. Towards the end of the DLC you get a kinetic hammer that lets you fight groups of them in combat. Considering the events of the DLC are revealed to be a Dying Dream, it's unknown whether or not they actually exist, though one of Mahler's audio logs seems to imply they did exist at one point and were where Mahler developed the technique she uses to hook Jacob's dying body up to a life-support system to keep him alive temporarily.
- Mini-Boss: A giant two-headed Biophage known as "Two-Head" serves as the game's "boss-like" enemy. They have powerful swings that will take you from full health to either dead or almost death in one hit, have about 5 times as much health as regular Biophages, cannot be grabbed with the GRP, and can't really be melee'd either unless they're stunned by enough gunfire. You fight 4 of them throughout the game, all in the last few levels. In two of these encounters you have to fight regular Biophages including Combustors while also dealing with the Two-Head.
- Miscarriage of Justice: Jacob becomes an inmate seemingly because he crashlanded on Callisto despite being told not to; he and his ship were nearly hijacked by members of the Outer Way, forcing him to crash-land to survive. However, later on, it seems clear that Jacob was arrested because he was complicit in smuggling the alien larva samples the UJC was secretly researching; Warden Cole wanted to cover his own behind and keep Jacob and Dani from exposing him.
- Multi-Mook Melee: The Riot Mode DLC adds "Riot Mode", a wave-based horde mode separate from the main game.
- Mythology Gag: Being a spiritual successor to Dead Space, veterans of the franchise can spot several references:
- The enemies' weakpoint being written in blood.
- The last shot of the game is a biophage lunging at the camera after the protagonist finishes a call.
- One of the Pre-Order bonuses’ happens to be a Retro B.I.P. uniform. It bears similarities to Issac Clarke's suit.
- No OSHA Compliance: Black Iron is a total deathtrap, even without the alien parasite currently infesting it. Throughout the prison, the player can find a lot of exposed machinery that you can take advantage of and use to kill enemies. However, there's absolutely nothing stopping you from accidentally walking into these hazards, which will turn you into mincemeat on contact.
- Oh, Crap!:
- At one point, Jacob has to make his way through a large drainage pipe in order to get to the Biodome. When the automated system suddenly announces that the gate valve has been opened, he turns around just in time to see a large wave of sewage water heading straight toward him. He barely has time to react before he's swept along with the water.
- Just before Jacob and Dani can call down a ship to escape, Warden Cole overrides the system and shoots the ship down, sending it crashing into the hangar where they're standing, forcing them to flee.
- Following on from the previous example, Dani, who has been an Action Girl up until this point, becomes noticeably unnerved when she realises they've fallen down into Arcas, an underground colony that was abandoned decades earlier. This only helps to establish the place's dreaded reputation.
- Orifice Invasion: A nasty version happens in the cinematic trailer, where an inmate is cornered by one of the monsters and has a slimy, tentacled parasite forcibly implanted into him through his mouth, nose, and right eye.
- Penal Colony: Crossed with Deadly Environment Prison. Callisto has been turned into a prison. In one of the trailers, several prisoners are shown as having frozen to death after trying to brave the frigid landscape outside Black Iron's main facility.
- Playing Possum: After the early 2023 patch, Biophages can sometimes mutate and get back up after being killed; they can even do this if you've already stomped the body for loot. About the only way to absolutely make sure this doesn't happen is to either impale them into spikes or give them a Turbine Blender death.
- Powered Armor: Jacob is eventually forced to don a UJC environmental exosuit when he needs to venture out into Callisto's frozen landscape. The suits not only provide oxygen to the wearer, they also offer thermal protection from the extreme cold of the moon's surface. They also have a built-in emergency beacon in the event the wearer's life is threatened. The suit also increases the amount of damage you can take, and doubles your inventory space.
- Punch-Clock Villain:
- Captain Ferris is a bit of a smug asshole, but overall isn't as sadistic or cruel as you'd expect from the head guard of a Hellhole Prison like Black Iron. His initial behavior toward Jacob is quite professional and cordial, even preventing Jacob from attacking Dani over her blowing up his ship and killing his partner, and even after he's ordered to capture Jacob and turn him in as an inmate, he still acts relatively professional. He doesn't really become hostile to Jacob until later, when he finds Jacob as an escaping inmate carrying a shiv, and starts questioning him over the coincidental timing of his arrival and the outbreak, clearly also using it as an opportunity to vent over his highly-stressful situation. His single-minded pursuit of him afterward can be explained by the fact that Jacob unleashed several mutants on him to escape, resulting in his infection and gradual mutation, leaving him with a bit of a chip on his shoulder. Overall he comes across as a guy who just wants to do his job and doesn't worry about any morally questionable orders he's given, which makes him no different from Jacob himself. He does become more Ax-Crazy after partially turning into a Biophage mutant, but at that point that sort of thing is rather understandable.
- One of the first audio logs, in fact, is him stating his mission objective and adding that he misses the previous warden, saying she was by the book and didn't make unusual requests like this.
- The Reveal:
- The Biophage virus was caused by larvae from a previously undiscovered alien creature native to Callisto. The larvae unleashed the infection upon the original colony seventy-five years earlier and wiped it out, forcing the UJC to cover it up. They have since been conducting experiments with the virus, building Black Iron as a front in order to reach the remains of the alien in the caverns below, and to provide a steady supply of test subjects.
- It's also revealed that Jacob knew that he was transporting something dangerous and illegal for the UJC, but unlike his co-pilot Max, who had apparently already figured out their cargo was really responsible for the recent "terrorist" attacks, Jacob opted to keep his mouth shut and not do anything about it in favour of a substantial payday. It's implied his newly installed CORE device implant was affecting his memories of this, as once he does remember, he's disgusted with himself and sets out to make things right.
- Shock and Awe: Jacob's primary hand-to-hand weapon is an electrified Stun baton taken from a dead guard.
- Sequel Hook:
- Warden Cole and the secret society responsible for the Europa and Callisto outbreaks are still at large, having used both outbreaks to gather more data in harnessing the Biophages. Meanwhile, Dani successfully escapes with Jacob's help, bringing with her evidence that can help expose the UJC's wrongdoings. Jacob is left behind on Callisto fighting a small horde of Biophage as Black Iron's self-destruct continues to count down, only to be contacted by Dr. Mahler regarding a possible last chance for them to both escape, as the mutated Ferris suddenly attacks him. This ends up being averted big time in the Final Transmission DLC, which reveals what really happened; Jacob was completely torn apart by the horde that attacked him, and Mahler retrieved his body and kept his mind alive just long enough to extract his memories. Mahler uploading said memories off-world, as well as Dani's escape, does still leave some room for a Sequel Hook however.
- In her research notes and Final Transmission, Dr. Mahler mentions that the UJC encountered a phenomenon similar to the Biophage outbreak in Paramo, an abandoned city in Peru which was built on the side of a volcano. This not only implies that the Biophage isn't native to Callisto, but that it's also present on Earth.
- Simple, yet Awesome: The humble assault rifle is this; as 11th Hour Superpowers go, it's no gravity gun, but it is almost certainly the best firearm you get. It does only marginally less damage than the revolver, killing Biophages in about 7-9 shots when fully upgraded, but has a much higher rate of fire, making it much more effective at staggering charging Biophages. Best of all, it is much more ammo-efficient than any other firearm; for most firearms, a single ammo drop only gives you about 1/2th the amount of ammo you'd need to kill an enemy. Assault rifle ammo drops typically give you more than twice the amount of ammo needed to kill an enemy. Once you get it, it's entirely possible to forgo melee combat almost entirely and more or less just shoot your way through the rest of the game (other than the two duels against Captain Ferris in his humanoid form, since he doesn't get staggered by gunfire). The only real limit on the weapon is the fact you only get it about halfway through the second-to-last level, and from that point there are less than about half-a-dozen combat areas between you and the Final Boss. However, with the addition of New Game+ in January 2023 the assault rifle can be made available from the start provided you've already played the game once, and will allow you to plow through the areas that gave you the most trouble before with relative ease, even on the hardest difficulty.
- Sinister Shiv: Jacob is provided his shiv by Elias who had been crafting it in secret. It acts as a tool for progressing through the game.
- Stout Strength: The fatter mutated inmates are noticeably tougher than the regular basic mutants, having more health and being better at blocking attacks.
- Surprisingly Realistic Outcome:
- While Jacob can fight reasonably well against a single Biophage in melee combat, shortcomings in the melee combat system mean that he quickly develops problems when dealing with multiple enemies at once. Given that Jacob is primarily just an ordinary person with no combat training or fighting experience, and he's fighting against monsters far stronger, fiercer, and with far greater endurance than an ordinary human, that's honestly true to life, and many of the game's other mechanics (Using stealth to take enemies out before they're aware of the player, using the GRP allowing you to toss enemies either into hazards or just far enough away to clear some space, and guns to fight enemies at a distance) would be steps an ordinary person in the same situation could be expected to take to prevent them from being ganged up on in a fight.
- Likewise, whilst Jacob proves himself to be an adapt and capable survivor, able to accumulate a small collection of powerful weapons to enable him to overcome the Biophages and their various mutations, that is against organic, living opponents, and even then it can be an uphill struggle for him unless he's careful with how he handles each encounter. The security guard robots, on the other hand, are mechanical, stronger than any human, mutant or otherwise, bulletproof, pack an Arm Cannon capable of blowing fist-sized holes in the target, lack any Achilles' Heel to break, with the broken ones littered about the prison implied to have been shut down during the initial outbreak by Cole, to prevent any variables from upsetting the experiment, and swiftly disabled by any freed prisoners. Even during late-game with better weaponry, Jacob's best option is to hide from them and avoid any conflict whatsoever, as they are impossible to defeat in a close-range fight, their entire purpose being to efficiently kill and detain prisoners like Jacob with ease. When Jacob and Dani are ambushed by two operational ones, they're instantly subdued without any way to fight back, with the only reason they're not killed being that Cole hasn't finished using them in his experiment.
- One of the symptoms of Biophage infection is an escalating fever over several days. An especially high fever will cause brain damage over time, with the parts of the brain responsible for maintaining basic life functions typically being the last to go. This explains why, despite the spectacular regenerative abilities of the Biophage, the victim loses their mind and becomes completely feral by the time the mutation is complete: By the time the transformation is finished, any part of the brain that housed memories, thoughts, feelings, or anything beyond the most primitive parts of the human psyche were destroyed during the fever. The Biophage has no ego or superego, just a raw, primal id.
- Swiss-Army Gun: The game's guns are 3D-printed uppers that slot onto the same receiver/grip; as a result, the revolver, sawed-off shotgun, and tactical pistol all use the same grip and it takes a second or two to swap the parts around. Later in the game you get a shotgun which can similarly convert into an assault rifle. You can quickswitch between your pistol and your longarm, but not between different pistols or between the shotgun and assault rifle.
- Teeth-Clenched Teamwork: In order to escape the prison and the Biophage outbreak, Jacob ends up having to work with Dani, the woman responsible for blowing up his ship and causing his copilot's death. Dani, for her part, thinks Jacob is a corporate stooge for his role as a UJC cargo transporter and was knowingly complicit in the outbreak in Europa that killed her sister. For his part, while Jacob eventually remembers that he did find out the UJC were smuggling something underneath the medical supplies he was allegedly transporting, he didn't dig any deeper than that owing to the paycheck, making him neither as guilty as Dani thinks nor as innocent as he wanted to believe.
- Title Drop: Warden Cole's third and final audio log has him order the prison computer to "activate The Callisto Protocol" which is the code name for his plan to release the Biophage infection at Black Iron, in order to find a subject who will become the progenitor for what he believes to be the next stage in human evolution.
- Turbine Blender: One particularly gruesome environmental kill involves Jacob getting too close to one of the turbines in the power plant. First his arm gets trapped, then the rest of his body is slowly dragged in and ground into bloody salsa. You can also do this to enemies as well.
- Tutorial Failure: A lot of the game's tutorials, while informative on the relevant topic, often come up in situations where the relevance is no longer there (as in, a tutorial for heavy attacks long after you just finished an enemy encounter, instead of during the encounter) or actively disrupts you with no warning (they like to instantly fill the screen with no buildup or option to ignore them). It makes for some unneeded complications in a combat system that's already a bit finicky.
- Voice with an Internet Connection: Shortly after meeting each other, Elias enables two-way communication between his and Jacob's CORE devices, allowing him to become this for Jacob and to guide him through the prison, as he has been there a long time and knows the layout very well. He remains in this role until his tragic death from asphyxiation on Callisto's surface.
- Zombie Apocalypse: Shortly after arriving at at Black Iron, the Biophage infection begins. The outbreak throws the entirety of Black Iron into disarray, with most of the staff and inmates having either succumbed to it or been killed by those who have. After just a few short hours, the entire prison is infected.
