Ough I was gonna talk about a bunch of different things, but then realised that just this one section became rather wordy. So I'll just keep it to this little bit.
I love love LOVE the sound design of the splatlings. Each splatling sounds unique in a way that so perfectly suits each one.
Heavy and Mini sound plastic-y, fitting their more toy-like appearance (Mini even has little rattle sounds added to it). The Order Splatling sounds subtly different from the Heavy, a bit more metallic? Not quite sure how to describe it, but it sounds exactly how it looks.
Nautilus and Hydra both sound metallic, being mostly metallic splatlings (go figure), but Nautilus sounds more hollow, like it's made out of thin metal sheets while Hydra sounds like an engine with how it purrs. Really highlighting the weight difference, despite the similar materials.
Ballpoint sounds plastic-y as well, but more? Dense? I guess? And the little mechanical clicks as it changes modes is just. Mwah! Beautiful!
Also did you know that there is an animation for Ballpoint changing it's modes? It's very fast and you can't really see it in regular gameplay because of the angle, but the Ballpoint does retract it's other barrels and sticks one of them out of the little hole in the casing for it's long range mode! That's so cool! I love splatlings!
Edit is a strange amalgamation of Heavy's plastic sounds, combined with Nautilus' more hollow sounds and Ballpoint's mechanical clicks. Really fitting it's gameplay, being the more mobile "traditional" splatling with a charge-based gimmick.
And despite the differences, they all sound so satisfying. The charge, the release, the singular uncharged bullets. They tickle my brain and satisfies my need for crunch