I just got Splatoon and it's pretty fun, to be honest. The weapons are interesting, the music is catchy, the character design is great, and it's nice to see a shooter that isn't a power fantasy for racists! I have some ideas for a potential sequel here.
Story: After the Inklings and Octarians put their differences aside (Octo Valley has become the aboveground Octo District of Inkopolis), an army of sea hares (Wikipedia entry here
) led by the Nudibranch Bros. (an obvious spoof of One Direction, their names [Alpheus, Pacifico, Lars, and Yabarak] spelling out APLY, the first 4 letters of Aplysiomorpha, the genus sea hares belong to) threaten to take over Inkopolis. It's up to Agents 1,2,3,4,& 5 (4 & 5 being the Squid Sisters' Octoling counterparts Tako and Yaki [from Takoyaki, fried octopus] who also host a news segment, theirs being related to the story, and who also play music, theirs being more similar to the songs in campaign mode and their songs also appearing in Octo District Turf Wars and Splatfests), led by Cap'n Cuttlefish and the newly reformed DJ Octavio to stop the gastropod invasion once and for all.
Music: All the tracks in the previous game appear. Some appear in Turf Wars and Splatfests (Including single player music from campaign mode), while others only appear in the jukebox (unlocked by default, and it contains the entire soundtrack of both games). The single-player campaign music is more Western pop inspired, with the final boss's second phase being the Squid Sisters's song from the original game, but with Tako and Yaki injecting a more electronic vibe.
Hubworld: Inkopolis is divided into 2 districts now, with Inkopolis Tower at the center. Squid District is the whole of Inkopolis from the original Splatoon, while Octo District, where the Octarians live, is basically a retreading of Squid District, but with a more industrial feel. Jellyfish appear on both sides.
Shops: All 4 shops in the original and Spyke's business appear, and their counterparts, which only take Super Sea Snails, appear in Octo District.
Mantis Strike: Owned by Shelby (Mantis Shrimp), this place has more powerful weapons, but at a higher cost.
Proteus Shirts: Owned by Nyx (Nautilus), this place sells higher-end clothing–At higher prices of course!
Chiton Footwear: Owned by Candra (Crab), this place is unusual that it sells items for cheaper. The items are usually lower-quality though.
Ice Cap: Owned by Clayton (Sea Angel), this place sells high-quality headgear for higher prices.
Star Swap: Owned by Spyke's cousin Aston (Sea Star), you can exchange Super Sea Snails for cash here.
Items: Not much, you can now keep Splatfest T-shirts if your team wins, and the Octoling armor (Purchasable from Nyx's shop) makes your squid form look like an octopus when you're wearing it.
Subtitles: I think the subtitles should be spoofs of other shooter titles, for example:
Calamari Of Duty
Cuttle of Honor
(I would put "Whalo" or something here but there's nothing in the plot about whales, maybe I should save that for the 3rd game.)
If you have any more ideas, let me know!