Return of the Mammalians

"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."

- 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 settings of the story) to defeat the Fuzzy Octarian army.

Story
An Inkling or Octoling accompanied by their "little buddy" Smallfry are scrap hunters who search for junk gems 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 adequate 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. 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 tentacle-shaped piece of Ooze takes Cuttlefish away from Agent 3, who loses their Hero 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 them that the Splatoon does 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 Ooze-covered rocket. Once they get to the top, they and the New Squidbeak Splatoon find Cuttlefish 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, aimed to 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. Now, 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, causing Smallfry to become Hugefry. They then fight 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.

Mechanics
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 and 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 cash, ability chunks, 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 then Alterna again.

Missions
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.

Quotes
"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

"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

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

Similarities with Octo Expansion
Return of the Mammalians bears multiple similarities to Octo Expansion. Both stages share their name with a playable game mode within their respective Splatoon game.

Story Mode Progression

 * 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
 * Mammalians has Power Eggs.
 * Octo Expansion has CQ Points.
 * Use of in-game currency is required to unlock or attempt missions, progressing the campaign.
 * In Mammalians, Power Eggs are also used to clear Fuzzy Ooze that block the way.
 * Both modes have a key NPC that guides the player throughout an area or splats them if they fail certain objectives (such as running out of ink or time).
 * Mammalians has O.R.C.A.
 * Octo Expansion has C.Q. Cumber
 * Both modes are underground, far below the sea level of Earth.

Final Stage
In both Octo Expansion and Return of the Mammalians, the player must face a continuous final stage before attempting to face the final boss of each campaign. The start of both stages remove the player's weapons and requires the player to re-equip their gear along the way. Both stages also feature an "unlimited use" section that allows special weapon use without losing special power.

Return of the Mammalians
The final stage in Mammalians is the Alterna Space Center with the inital Alterna Space Center: Entrance starting the player with no gear.

The section for unlimited special weapon use is The Spirit Lifter: First Class with Zipcaster as the weapon.

Octo Expansion
The final stage in Octo Expansion is Deepsea Metro Escape with the initial areas of Coccyx Phase and Villi Phase starting the player with no gear.

The section for unlimited special weapon use is Diaphragm Phase with Inkjet as the weapon.

Penultimate Missions
Both of these sequences feature two songs written by the game's main idol group.

The penultimate mission uses different music for each section: the first playing a modified version of the enemy's theme, and the second play's the idol's theme.

In both final missions, the successful final attack grows so powerful that the attack damages the game UI in some way.

In both final missions, being splatted or running out of time will show an additional cutscene of the world being destroyed before showing the 'Continue?' screen.

Return of the Mammalians
The first mission is Rocket Battle, using Bear with Me as the theme.

The final mission is Return of the Mammalian (mission), using Calamari Inkantation 3MIX as the theme. DJ Octavio's Ink Vac destroys the game UI as the attack power increases.

Octo Expansion
The first mission is Sanitized Agent 3 using Splattack! (Octo) as the the theme.

The final mission is Turf War (Octo Expansion) using Fly Octo Fly ~ Ebb & Flow (Octo) as the theme. Pearl's Princess Cannon destroys the game UI as the attack power increases.

Changes after finishing Story Mode
After completing Story Mode, there are a few changes that will appear in the rest of Splatoon 3.


 * Alterna - the original Mr. Grizz statue can be interacted with to replay the final section.
 * It is found behind the camp of the New Squidbeak Splatoon
 * Alterna - if all areas are 'surveyed', the Shell Drone appears on the platform near the campsite.
 * Alterna - if all levels (kettles) are completed, the Secret Kettle appears behind the spawn point
 * The kettle sends the player to After Alterna and does not appear on the map
 * Alterna - the rocket in the center of Alterna will turn blue.
 * Multiplayer - Li'l Judd will now wear a headset.
 * Splatsville - when standing at the Anarchy Splatcast studio, zooming into the studio will cause Deep Cut to wave with enthusiasm at the player (after a few seconds).
 * This is compared to a simple "nod" the player receives before completing Story Mode.
 * Grizzco Industries - the statue of Mr. Grizz is replaced by a fish with a bear in its mouth
 * The fish is modelled after Smallfry in its Hugefry form
 * The model of Mr. Grizz is smaller
 * The original statue is located behind the camp of the New Squidbeak Splatoon

Comparison with other Splatoon titles
Return of the Mammalians contains some changes that make it unique in the Splatoon series.

Firsts

 * 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.
 * Unlike Octo Valley and Octo Canyon, the player can use a non-hero weapon in this campaign.
 * Octolings are playable in the single-player campaign of the base game for the first time.

Design and Progression

 * 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
 * It is the fewest number of levels needed in the series
 * It is one less level required than in the Octo Expansion.

Trivia

 * 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".
 * In-game, the torn down version is a "standard" form while the other is part of the upgradable Hero set.
 * 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 loudspeaker system to the Alterna Space Center
 * Various notification sounds and human speech in English can be heard reporting on the status of the rocket launch.
 * 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.
 * Big Bubbler, while not available for use by the player, is used by Fuzzy Octolings in the final section of After Alterna.
 * 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.