Return of the Mammalians

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Return of the Mammalians
S3 art 2D story mode H.jpg
Type Single-player campaign
Players 1
Weapons Various
Controllers Nintendo Switch Joy-Con with grip.png Joy-Con
Nintendo Switch Pro Controller.png Nintendo Switch Pro Controller
Release Date Launch
This article is about the single-player mode of Splatoon 3. For the mission, see Return of the Mammalians (mission).
Join Agent 3 and the New Squidbeak Splatoon in a hairy fight against the unruly Octarians. Discover the secrets of Alterna and the Fuzzy Ooze.
Splatoon's official website

Return of the Mammalians is a single player game mode in Splatoon 3. It involves the player donning a Hero Suit and venturing into the Crater and Alterna (the setting of the story) to defeat the Fuzzy Octarian army.


An Inkling or Octoling, accompanied by their "little buddy" Smallfry, are scrap hunters who search for junk gems by day and splat it up in Turf Wars on the side. When they go through a manhole, they meet Craig Cuttlefish on the other end at the Crater, who dubs them the new Agent 3 of the New Squidbeak Splatoon. He explains that the New Squidbeak Splatoon's continued mission is to stand in opposition of the unruly Octarians, who are suspected to be behind the recent disappearance of the Great Zapfish from Splatsville.

The areas throughout the campaign have a large amount of Fuzzy Ooze. To get through areas, Agent 3 has to take care of the Fuzzy Ooze, which Smallfry can eat as long as they have the right amount of Power Eggs. Cuttlefish also notices that the Octarians have fur grown over their body, as opposed to their previous appearances where they were smoother. When Cuttlefish tries to contact Agent 1 and Agent 2 to come pick them up, DJ Octavio intervenes, but Cuttlefish dismisses it as his radio being broken.

After reaching the center of the Crater, DJ Octavio appears in his battle mech named the Octobot King L3.Gs, trying to confront the two for the recent disappearance of his Octarian army, but when asked about the stolen Great Zapfish, states that he does not even know about it this time, and engages Agent 3 in a fight. Upon being defeated, Octavio tells Cuttlefish and Agent 3 that he indeed did not steal the Great Zapfish, and Cuttlefish thinks that someone else might have done it, but before they can continue, the ground beneath them collapses as Fuzzy Ooze flows out. A piece of Ooze takes Cuttlefish away from Agent 3, who loses their Hero's Suit and Power Eggs in the fall. Agent 3 then wakes up in Alterna, where they are greeted by the New Squidbeak Splatoon comprised of the old Agent 3 (now Captain) and the Squid Sisters.

The new Agent 3 is also aided by a robotic assistant named O.R.C.A., who helps guide them through Alterna.

At the end of Site 1, Future Utopia Island, Deep Cut makes their entrance and makes it clear that all the loot in Alterna belongs to them. Later, each of them guards one of the three 'treasures' in the area and Agent 3 has to defeat them to continue.

After collecting all three parts of the Treasure, Callie and Marie assemble it into a lawn mower-like tool, which the Captain uses to cut off the fur near the rocket at Alterna Space Center so the team can go there and save Cuttlefish.

The Captain gets hurt while using the tool, and it also breaks down. Soon after this, Deep Cut appears again trying to take back the treasure, but Marie tells Deep Cut that they do not need the treasure and that they can have it back. Deep Cut then asks Marie to be their boss, who reluctantly accepts.

On their way to the rocket, the party overhears that Mr. Grizz plans to use Cuttlefish and the Golden Eggs (collected by the unwitting Inklings and Octolings in Inkopolis and Splatsville working in his company) to 'restore the balance of the world'. When asked about the reason for hunting treasures, Shiver and Frye explain that they want to sell the treasure to help those in need in Splatsville, while leaving little to themselves, which makes Callie and Marie respect them.

After completing all the sites, Agent 3 has to get on the rocket which is covered by Fuzzy Ooze. Once they get to the top, they and the New Squidbeak Splatoon find Cuttlefish all dried up and lifeless, as a result of being dehydrated by Mr. Grizz. Grizz, now revealed to be a grizzly bear, then appears and escapes on the rocket, which will then spread Fuzzy Ooze all over the Earth and bring forth a new era of mammalian dominance.

The Captain drops a tear on Cuttlefish's body, which makes him come to his senses. Deep Cut appears again and helps Agent 3 and Smallfry reach Mr. Grizz's rocket. There, Agent 3 and Mr. Grizz engage in a fight. After having some of his Fuzzballs splatted, Mr. Grizz knocks Agent 3 and Smallfry out from his rocket as he absorbs the Fuzzy Ooze and plans to send it on the Earth himself. Soon, DJ Octavio, now knowing who the true culprit is, appears in his modified Octobot to save the two. DJ Octavio, the Squid Sisters and Deep Cut then play the Calamari Inkantation 3MIX together, and Smallfry becomes Hugefry shorty after that, who then fights Mr. Grizz as DJ Octavio and Agent 3 vacuum the Fuzzballs on Mr. Grizz's body, before blasting him back with the ooze, defeating him. After emerging victorious, DJ Octavio, Agent 3 and Smallfry return to the Earth together.



Comparing to the Hero Mode of the previous two games, Return of the Mammalians has a less linear progression similar to the Octo Expansion. Upon entering a mission, O.R.C.A. explains the rule of the level with dialogue and prompts the player to select one of the sets of weapons available. Different sets of weapons may have different Power Eggs rewards. Some missions also cost Power Eggs to play, and/or have special conditions that will cause the player to get splatted if they fail.

The areas in this mode are covered in Fuzzy Ooze, which serves as the obstacle blocking the path to other areas, rather than having the missions locked themselves. The player needs to use the Power Eggs they collect from the missions to clear them in order or progress.

The map screen in each of the sites tracks how many of each type of item the player has found on the overworld (loot anchors that contain decorations, golden records, Sardinium, and Sunken Scrolls). The map highlights areas with unobtained items to find in green, labeled as Areas of Interest, whereas it marks areas which the player hasn't been to yet with black striped squares labeled Parts Unknown. If the player fully collects all items in a site and goes to every possible part of the map so that there are no longer any black squares, the site becomes marked as "Surveyed". Marie will award the player with a piece of the map of Alterna as a sticker if they survey that site.

Fully surveying all sites causes a Shel-drone to appear. Each day the player can charge this drone by using 999 power eggs. The following day, the drone will send an item to the lobby terminal. These items include Tableturf Battle card packs, and meal tickets, as well as decorations that can only be found in Alterna. This is currently the only way to get duplicates of these decorations. If the Shel-drone doesn't appear after the player surveys every area, they will need to go back to Splatsville and Alterna again.


Prologue: The Crater

Site 1: Future Utopia Island

Site 2: Cozy & Safe Factory

Site 3: Cryogenic Hopetown

Site 4: Landfill Dreamland

Site 5: Eco-Forest Treehills

Site 6: Happiness Research Lab

Finale: Alterna Space Center


Regular enemies

This table is sorted by order of appearance. Enemies marked with * are newly introduced in Splatoon 3.

Image Name Description Debut
S3 render Octotrooper.png Fuzzy Octotrooper The basic grunts of the Octarian army, Octotroopers stand on small machines that allow them to shoot single, very slow ink globules. They have very little health and mobility and so are easily defeated, but may pose a threat in numbers. No. 1 Octarians in the Crater? YIKES!
FuzzyBlobbyOctotrooper.jpg Fuzzy Blobby Octotrooper Octotroopers that ride a different machine resembling a gumball machine. They act and look almost identically to their regular versions but shoot a duo of shots that bounce along the ground. These can deal a lot of damage in numbers but are also susceptible to gravity. No. 1 Octarians in the Crater? YIKES!
S3 Tableturf Card Octocopter.png Fuzzy Octocopter Flying enemies propelled by their helmets. They hover above the ground and shoot at Agent 3 on sight, but their projectiles and general flying speed are slow, like Octotroopers. No. 3 Boxes Locked! Keys, Please!
Squee-G Splatoon 2.jpg Squee-G Although incapable of dealing damage, these very rare small robots serve as nuisances, attaching to walls and automatically sucking up Agent 3's ink. They can sometimes carry items and slow down upon being attacked. 0101 Get to Know Alterna, Your Only Choice
S3 Tableturf Card Octopod.png Octopod Small metallic creatures that run around in sneakers. Octopods jump to attention upon seeing the player. Upon reaching them, they explode in Octarian ink, dealing some damage. They can be attacked to be defused. They appear to be Octorpedoes on legs. 0102 Octopods at Rest Tend to FLIP OUT!
S3 Tableturf Card Oversized Octopod.png Oversized Octopod* Giant Octopods that move and attack in a similar way to their smaller counterparts. However, they are slower but require much more damage to detonate, having a much larger blast radius as well. 0102 Octopods at Rest Tend to FLIP OUT!
S3 Tableturf Card Octosniper.png Fuzzy Octosniper Elite enemies that shoot long, thin, and very powerful shots of ink, similar to chargers, while stationed on unmoving platforms. Like charger users, they have an extremely long line of sight but are mostly incapable of close-quarters fighting, while their shots require some time to charge and are marked with a laser line. 0104 Doors, Doors, Doors! And More! (Doors)
S3 Tableturf Card Octocommander.png Fuzzy Octocommander Large stationary enemies that are very similar to Octosnipers. They can only rotate in place and use giant splatlings to attack quickly over a large range. However, they take a while to recharge, leaving them wide open. 0104 Doors, Doors, Doors! And More! (Doors)
S3 Tableturf Card Shielded Octotrooper.png Fuzzy Shielded Octotrooper Octotroopers with shields in front of their machines. The shield can be destroyed after taking a lot of damage, but their exposed backsides are their weak spots, easily hit after being distracted, such as by Smallfry. Also appears in Octodiver and Twintacle Octotrooper forms. 0109 The String's the Thing
FuzzyRocketOctocopter.jpg Fuzzy Rocket Octocopter Darker versions of Octocopters that have thrusters attached to their helmets. Although they are no stronger than normal, they can quickly dodge left and right, making them a nuisance to defeat. 0109 The String's the Thing
S3 Tableturf Card Amped Octostamp.png Fuzzy Amped Octostamp* Stronger Octostamps that are recognisable by their headphones. They have a cover over their weak point, requiring more damage to break, and send out a damaging shockwave on contact with the ground similar to the Wave Breaker. 0110 Deadly Dance Hall - Jump, Jump!
S3 Tableturf Card Twintacle Octotrooper.png Fuzzy Twintacle Octotrooper Stronger Octotroopers with two tentacles. These enemies have better mobility than the normal Octotrooper and greater ink-firing capability, similar to a splatling, but are still easy targets. 0201 Twirling, Swirling, Whirling
S3 Tableturf Card Octomissile.png Fuzzy Octomissile Little explosive missiles with a tentacle in the middle. They spawn infinitely and burst with ink on contact, but can be defeated simply by being attacked. 0205 Tread Heavily
S3 Tableturf Card Octozeppelin.png Fuzzy Octozeppelin Giant airships themed after Octarians with a single tentacle sticking out the top. They spawn infinitely, using their propellers to spray ink behind them, and are invulnerable apart from their tentacle. 0302 They Said We'd Have Flying Cars, and We Do! Kinda!
FuzzyOctowasher.jpg Octowasher Indestructible spinning torrents of ink that appear as damaging barriers. They deal fatal damage on contact and block shots, meaning they can only be avoided. 0304 Try Curling! Alterna's 11th Most Popular Athleisure Activity!
S3 Tableturf Card Octohopper.png Fuzzy Octohopper* Bouncing Octotroopers that follow Agent 3 on sight. Although they are as weak as regular Octotroopers, they are persistent and attack with slosher-like ink flings which deal a lot of damage. 0402 Octohoppers Don't Have a Sense of Humor (and They Hate Puns)!
S3 Tableturf Card Octoballer.png Fuzzy Octoballer Inky bowling balls populated by Octotroopers that spawn infinitely and leave a trail of ink behind them. They can only be destroyed by attacking the Octotrooper as normal. 0403 Let's Put a Pin in That
S3 Tableturf Card Octodisco.png Fuzzy Octodisco* Flying spherical Octarians that look similar to disco balls. Instead of attacking Agent 3, they hover over other enemies and form a shield like the Big Bubbler. In this state, they can only be attacked from above, but the shield breaks if the enemy inside is defeated. 0407 Charge Now, Splat Later
S3 Tableturf Card Octoling.png Fuzzy Octoling Octarian variants of Inklings that act as elite forces en masse and can utilise a wide variety of main, sub, and special weapons. Dark-haired Elite Octolings are much harder to defeat and act similarly to human opponents in multiplayer modes. 0411 Stamp 'Em Out
S3 Tableturf Card Octostamp.png Fuzzy Octostamp Cuboid, machine-like creatures with inky faces. Although they are not fast, they can leap into the air and face-plant the ground, dealing fatal damage. They can only be defeated from behind, which is exposed by their method of attack. 0411 Stamp 'Em Out
FuzzyRocketTwintacleOctotrooper.jpg Fuzzy Rocket Twintacle Octotrooper Noticeably darker Twintacle Octotroopers. They have the same capabilities as normal Twintacle Octotroopers but with jet thrusters on their machines, making them capable of fast dodges. 0501 Trouble Round Every Corner
S3 Tableturf Card Flooder.png Flooder Huge machines on stilts that rain down Octarian ink from under them and move in set patterns. They charge at Agent 3 on sight and can defeat them instantly if not distracted by Smallfry, but their tops also act as platforms that can hold items and other mechanics. Big Flooders are even taller and harder to scale. 0505 A Compulsive Collector's Paradise
S3 Tableturf Card Octobomber.png Fuzzy Octobomber Large flying Octarians similar to improved Octocopters. They hover around and shoot Splat Bombs out of their helmets which detonate fatally one second after landing. However, they are large, slow, and unwieldy, making them obvious targets. 0509 Low Viz, High Risk
FuzzyRocketOctobomber.jpg Fuzzy Rocket Octobomber Darker variants of Octobombers that can use the rocket thrusters on their helmets to quickly dodge to the side when being attacked. Their attack pattern has not changed, however. 0509 Low Viz, High Risk
S3 Tableturf Card Tentakook.png Fuzzy Tentakook Extremely rare little Octarians that hide important items and give chase on sight. They use their ink-powered rollerskates to cover their tracks and can drop Splat Bombs behind them. They are very fast and can only be caught by swimming in ink. 0611 Don't Tease with the Keys
Splatoon 2 Octorpedo Model.png Octorpedo Missiles filled with Octarian ink fired by Mr. Grizz. Acting like flying Octopods, they home in on Agent 3 and explode, but can be easily shot down. However, amongst the rest of the boss battle, they can serve as major distractions. Rocket S3 Icon Boss Black.svg 1 Rocket Battle
FuzzyOctodiver.jpg Fuzzy Octodiver Octotroopers wearing snorkels, which allow them to breathe under their ink. They pop out without warning to attack and can dive to hide like Agent 3. Also appears in Shielded Octotrooper and Twintacle Octotrooper forms.


Image Name Description Debut
Splatoon 3 Octobot L3.Gs.png DJ Octavio and the Octobot King L3.Gs The leader of the Octarians in his signature machine, now with added legs and new attacks to make up for no longer being powered by the Great Zapfish. Like in previous appearances, Octavio attacks with a variety of fist attacks which must be avoided or shot back to damage him. In later phases, he utilises Ink Vac and Wave Breaker attacks as well. Crater S3 Icon Boss Black.svg Octobot King L3.Gs
S3 Frye boss battle introduction.png Frye* The first member of Deep Cut. She rides on the remains of the Octostomp out of range and attacks by shooting dozens of moray eels at Agent 3, which must be avoided or shot back to damage her. When stunned, the player must scale the Octostomp to damage her directly, after which she adds a variety of extra eel attacks to her move set. 02 S3 Icon Boss Black.svg The Future Stares Back
S3 Shiver boss intro.png Shiver and Master Mega* The second member of Deep Cut and her shark, which she rides mostly out of range of attack. Although they can be damaged while circling the arena, it is easiest to attack Master Mega when it charges onto the arena like the Reefslider, at which point Shiver can be attacked directly. In later phases, they jump between ink tornadoes around the arena and attack much faster. 04 S3 Icon Boss Black.svg The Pursuit of the Precious
S3 Big Man Boss Intro.png Big Man* The third and final member of Deep Cut. He transforms into a shadow and floats around the arena, leaving ink behind. When attacked, the shadow splits into smaller ones which attack with various bomb blasts. The real Big Man shadow is identified through the Squid Sensor, whereas fake ones explode. In later phases, the shadows attack faster and with more bomb types. 06 S3 Icon Boss Black.svg The Obscurest Chiaroscurist
Mr. Grizz.png Mr. Grizz* He is Ursine Anomaly #3 and CEO of Grizzco Industries who has harvested Golden Eggs and stolen the Great Zapfish in order to return mammals to the world through his Fuzzy Ooze. Agent 3 must dodge his many attacks and clear Fuzzy Ooze with Smallfry to be able to attack Grizz directly, after which he intensifies his attacks. In the second half of the battle, Agent 3 must work with DJ Octavio to use the Octobot King L3.Gs' Ink Vac and absorb and shoot out the Fuzzballs on Grizz's body within 3 minutes and 33 seconds, all while avoiding space debris. Rocket S3 Icon Boss Black.svg 1 Rocket Battle


SRL historian here with a pro tip. Want to learn about the weird world of Alterna AND brush up your skills with all kinds of weapons and varied terrain? Check out Story Mode! Just follow the strange old man into the Splatsville sewer to get started. Wow, new sentence.

Another Story Mode tip: most stages allow you to choose from multiple weapon loadouts. So you can sharpen your skills AND take advantage of a weapon's particular strengths to survive. That said, sometimes you'll have nothing to rely on but your wits... and maybe a Zipcaster.

— @SplatoonNA on Twitter[1][2]
It's not all multiplayer mayhem in #Splatoon3, you know? Dozens of single-player stages filled with unique tricks, tests and... hairy Octarians await in Story Mode.
— @NintendoEurope on Twitter[3]


Main article: Badge#Story Mode

Doing certain things in Return of the Mammalians will reward the player with special badges that they can use on their Splashtag.

Return of the Mammalians Badges
S3 Badge DJ Octavio.png DJ Octavio Defeated! Defeat the Octobot King L3.Gs in the Crater
S3 Badge Cuttlefish.png Story Mode Cleared! Complete the Alterna Space Center sequence
S3 Badge Callie.png Max Hero Level Achieved! Collect the maximum of 99 Upgrade Points
S3 Badge Marie.png Max Hero Level Achieved!
S3 Badge Mr. Grizz.png Secret Kettle Found and Cleared! Unlock and clear After Alterna



Promotional images


  • This is the first single-player campaign that does not have "Octo" as the first word.
  • This is the first single-player campaign to not include any missions based on any Turf War stages.
  • This is also the first campaign to not include a series of levels dedicated to the Octolings. Furthermore, it is the only campaign that does not introduce the Octolings via a mini-cutscene.
  • This is also the first single-player campaign to involve and have the player to go into space.
  • Agent 3 has two styles of the Hero Suit. A post on Nintendo's official website hinted that they are "each suited to different situations".[4]
    • In game it turns out that the torn down version is a "standard" form while the other is part of the upgradable Hero set.
  • Unlike Octo Valley and Octo Canyon, the player can use a non-hero weapon in this campaign.
  • Additionally, this story mode bears multiple similarities to the Octo Expansion:
    • The player can choose between different non-Hero weapons.
    • Both modes have a similar interface, a variety of mission conditions and heightened freedom as opposed to the previous two Story Modes' linear progression.
    • Both modes have a form of currency that is used to gain access to new areas and missions as well as playing missions (CQ Points and Power Eggs). Not all missions in Return of the Mammalians cost Power Eggs to play, and instead, Power Eggs are primarily used to clear Fuzzy Ooze that block the way.
    • Both modes have a key NPC that, besides guiding the player throughout the area, will also splat them if they fail certain objectives or missions (such as running out of ink). They are C.Q. Cumber and O.R.C.A. respectively.
    • Both modes are underground the normal sea level.
    • Both modes have a final part that has multiple continuous stages before the Final Boss. They are the Deepsea Metro Escape and Alterna Space Center respectively.
    • The final mission (Turf War and Return of the Mammalians respectively) of both modes have the player stop the antagonist within a time limit.
      • Failing either of these by either being splatted or running out of time will show an additional cutscene of the world being destroyed before showing the usual 'Continue?' screen.
      • In both cases, the successful final attack (Pearl's Princess Cannon and DJ Octavio's vac spit) eventually grow so powerful that they damage the game UI in some way.
      • Both share their name with a playable game mode.
  • Octolings are playable in the single-player campaign of the base game for the first time.
  • After beating the Story Mode, the statue of Mr. Grizz at Grizzco is replaced by a fish with a bear in its mouth, modeled after Smallfry (in its Hugefry form) and a smaller Mr. Grizz. The original statue is located behind the camp of the New Squidbeak Splatoon and can be interacted with to replay the final section.
  • Before Version 1.1.1, if the player closed the game or entered sleep mode during Deep Cut's news broadcast directly after beating the final boss, they would be forced to replay the entire final section due to a glitch.
  • Cuttlefish's quotes about Octarians or squid references do not change when the player is an Octoling.
  • Many mysterious sounds can be heard in Alterna, but are hard to hear and are distorted. Extracting the game's audio files has found some of this ambient noise to be announcement messages sent over a somewhat broken-up loudspeaker system to the Alterna Space Center, with various notification sounds and human speech in English reporting on the status of the rocket launch.
  • After completing the final mission, the rocket in the center of Alterna will turn blue.
  • Return of the Mammalians is the second single-player campaign in the Splatoon series to have one or more groups of levels that do not contain a boss level. The first single-player campaign to do this is Octo Expansion.
  • As level progression in Return of the Mammalians is linked to collecting Power Eggs rather than completing levels, the ending can be reached by completing a minimum of 15 levels (the five Crater missions, the three Deep Cut bosses, and the seven stages of the space center and the rocket), the fewest in the series and one less than in the Octo Expansion.
  • The Booyah Bomb and Tacticooler special weapons are the only ones in the game that were available at the game's launch to not appear in any way in Return of the Mammalians. Booyah Bomb was most likely excluded due to the lack of a Booyah signal in this mode, and Tacticooler's primary function of providing a boost to teammate's abilities being non applicable in single player probably lead to it not being included.
    • Big Bubbler, while not available for use by the player, is used by Fuzzy Octolings in the final section of After Alterna.


Names in other languages

Language Name Meaning
Japan Japanese 哺乳類の帰還
honyūrui no kikan
Return of the Mammals
Netherlands Dutch Terugkeer van de Mammalianen Return of the Mammalians
Canada and France French Le retour des mammifériens The return of the Mammalians
Germany German Rückkehr der Mammalianer Return of the Mammalians
Russia Russian Возвращение молокоедов
Vozvrashcheniye molokoyedov
The return of the milk eaters
China Chinese (Simplified) 哺乳类的回归
Bǔrǔlèi de huíguī
Return of the Mammals
Hong Kong Chinese (Traditional) 哺乳類的回歸
Bǔrǔlèi de huíguī
Return of the Mammals
South Korea Korean 포유류의 귀환
poyuryu-ui gwihwan
Return of the Mammals

External links