Splatoon is primarily a team-based third-person shooter which is playable by up to eight players in 4-vs-4 matches, although the game also features a single-player campaign. Players control characters called Inklings, wich can change between human form and squid form. Transforming into a squid allows players to swim through ink of their own color, even up walls and through grates, hiding from the enemy and replenishing their ink supply in the process.

After the Great Zapfish, Inkopolis' primary power supply, is stolen, Cap'n Cuttlefish employs a Splatoon of Inklings to travel to the Octarians' secret underground base and retrieve it. Players assume the role of Agent 3 of the New Squidbeak Splatoon and traverse the treacherous landscape of Octo Valley in order to reclaim various lost Zapfish, Sunken Scrolls, and Power Eggs.