Ink

Ink is the main projectile used in the game Splatoon as well as a way to get around. It comes in a variety of team-based colours. Ink stains walls and the ground, but goes through grates and can't be splattered on barrels, mats and glass. It allows the player to camouflage, and ambush enemies.

Purposes
Ink can be used in a variety of ways, including as a projectile. Being hit by enemy Ink causes Inklings to take damage and become visible to their opponents on. After taking enough damage, Inklings will be splatted and eventually respawn. When attempting to swim or walk through enemy Ink, Inklings take damage, though this alone cannot splat them. Their movements also become very slow, and if they are in squid form, they will be forced back into humanoid form. Equipping gear with the Ink Resistance Up ability helps to reduce the effects of being in enemy Ink, and Defense Up reduces damage taken from being hit by it.

Ink can also be fired at various ink-able surfaces. Once a surface is coated in Ink, Inkings in squid form can swim through it, allowing them to move more quickly and climb up walls. When staying still in their own Ink, Inklings in squid form can hide and ambush enemies, and when moving they will only create small ripples. Equipping gear with the Ninja Squid ability hides these ripples, further improving the wearer's ability to move undetected.

Main Weapons and Sub Weapons both require Ink, with the specific amount needed varying between different weapons. Ink requirements can be reduced by equipping the Ink Saver (Main), Ink Saver (Sub), Last-Ditch Effort, and Comeback abilities. If Inklings do not have enough Ink to use a weapon, they will be warned of it and their Ink Tank will flash with a large red "X". Ink will slowly refill automatically, but swimming one's own Ink in squid form will refill it much faster. Ink Recovery Up will increase the speed at which Ink is regained.

In Octo Valley, Ink is used in even more ways. Inkrails exist for transportation, as Inklings in squid form can use them to get to otherwise inaccessible areas. Sponge Blocks, when squirted with Ink, will expand and then can be used as a platform. Splat-Switches, when covered with Ink, will cause objects to move. Ink can also be used to spin Propellers, which power the movement of various platforms.

Colors
Colors used in-game include the following:

Regular Battle

 * Bubblegum Pink
 * Pink
 * Orange
 * Yellow orange
 * Lime green
 * Emerald green
 * Teal
 * Blue
 * Violet
 * Sky Blue (Introduced in Version 2.0.0 along with Squid Girl crossover DLC)

Ranked Battle
Includes all the colors from Regular Battle, plus:
 * Red orange
 * Yellow
 * Mint
 * Green
 * Sea green
 * Light blue
 * Dark blue
 * Fuchsia
 * Magenta
 * Dark Violet

Octo Valley
Includes some colors from Regular and Ranked battles, plus:
 * Neon green
 * Neon orange
 * Cyan
 * Dark fuchsia (exclusive to Octarians)

Splatfest
Some Splatfests feature exclusive colors or colors that have previously not been featured in online battle modes.
 * Dark orange (Lemon Tea) - exclusive
 * Tan (Milk Tea) - exclusive

Color Pairings
In the game, all ink colors are locked to face another ink color, usually one that is the opposite of the color the player is. Some can have multiple pairs, but others will have only one. This does not apply for Splatfests, as all colors are locked in place of the two team's color. In Octo Valley, the opposing color will always be dark fuchsia.

Trivia

 * According to Sunken Scroll 7 and Callie and Marie, ink vanishes after every game.
 * Splatoon is capable of rendering any color of ink. NWPlayer123 replaced the colors for certain Octo Valley missions to experiment with new ink colors.