Rumors and leaks

There are a few rumors and leaks regarding Splatoon content. Some are created by the community with others being sparked by the developers themselves.

Ongoing
This is a list of rumors/leaks that have neither been confirmed true nor false.

OatmealDome leak on reddit
In August 2017, reddit user OatmealDome made two posts with datamined information from Splatoon 2, which has not been officially revealed at the time. Many upcoming Splatoon 2 weapons and gear have been found in the game's files.

March 15th 2018 Update
On March 15th, 2018, LeanYoshi, who performed the data mining for weapon stats, has updated the weapon loadouts for all previously leaked weapons :

April 24th 2018 Update
On April 24th, 2018, LeanYoshi updated the data with a few more changes, as well as updating the database with the 3.0.0 changes:

Confirmed
This is a list of rumors/leaks that have been confirmed true.

Prima Strategy Guide "Coming Soon" section
The Prima Strategy Guide for Splatoon includes a "Coming Soon" section which shows off weapon and stage DLC. Weapons: Carbon Roller, Custom E-liter 3K, E-liter 3K Scope, Inkbrush, L-3 Nozzlenose, N-ZAP '85, N-ZAP '89, Rapid Blaster Deco and Splash-o-matic. Stages: Bluefin Depot, Kelp Dome, Camp Triggerfish, and Port Mackerel. There are also two images of Tower Control.

Datamine DLC leak
NWPlayer123 Datamined Splatoon and leaked information about upcoming DLC weapons, stages, and modes. Also, some pictures and explanations about the new ranked mode games: Tower Control and Rainmaker.

The leaker also uploaded a video of the Sploosh-o-matic, one of the leaked unreleased weapons, after using live memory edits to add it in.

The following content was revealed due to this datamine:

Weapons

 * Sploosh-o-matic
 * Neo Splash-o-matic
 * N-ZAP '89
 * Custom Dual Squelcher
 * Luna Blaster
 * Carbon Roller
 * Octobrush
 * E-liter 3K Scope

Stages

 * Moray Towers
 * Camp Triggerfish

Modes

 * Rainmaker's description and gameplay mechanics

Version 2.0.0 Datamining
After the release of Version 2.0.0, NWPlayer123 and Guy Perfect once again dug into the data and found more information regarding unreleased content, including weapons, stages, gear, character models and game modes.

Sloshing Machine Datamining
In a similar vein to the Version 2.0.0 datamining, NWPlayer123 posted photos and video of a new Slosher variety, the Sloshing Machine, as well as other minor additions in 2.2.0.

Squid Sisters amiibo
A Twitter post by NWPlayer123 on January 30, 2016, showed the results of continued datamining: there may be new amiibo coming for Splatoon, called "AmiiboIdolA" and "AmiiboIdolB" in the game's files. According to her, they could be Squid Sisters amiibo, hence the names.

On April 30, 2016, Splatoon JP finally announced that Squid Sisters's Amiibo will be released at 7th July 2016.

Busted
This is a list of rumors/leaks that have been confirmed false.

Cheat code
Some days after the game's launch, players noticed that some Sunken Scrolls, as well as signs on Inkopolis Plaza, contain what appears to be arrows pointing up, down, left or right.

On the 9th of June, 2015, the official Splatoon Facebook page made a joke post referencing how some Facebook users accidentally type Google search queries on their Facebook profiles. This joke, however, sparked curiosity among fans, as the "search" was for "Squid Jump cheats". Naturally, Nintendo staff themselves would not be searching for cheat codes on a game made by their company, meaning the post was placed there on purpose, likely to hint players about the existence of a code hidden inside the game.

On top of this, the official Splatoon Tumblr account made a post about how players can press on the Plaza to look around, and how this serves the additional purpose of getting information on Miiverse posts. It also mentioned that it "may also have another use", which remains unknown to this day.

As of yet, no code has been found, and it is unknown if there is any relation between the arrows, the rumored code, and the rumored extra function of the button, or if any secret exists to begin with. Players have since been attempting to figure something out by input the arrow's directions during different parts of the game, mostly the Squid Jump minigame, but without luck.

However, Splatoon Ikasu Artbook definitely shows that it simply is a stylized spelling of "ブイヤベース" (Booyah Base) in Inkling.

Super Mario Sunshine DLC
There was a "leak" on the internet that Super Mario Sunshine amiibo DLC was coming to Splatoon. Only a single image existed regarding this supposed leak. It has since been proven fake, with the author of the leak releasing the images they used to create it.

(New) Super Mario Sunshine DLC
During July, a new Super Mario Sunshine amiibo DLC rumor with several images were found. These images supposedly depicted new Sunshine-related gear and Octo Valley missions. August 14th passed, and nothing like this was added, likely confirming it as false.