Yeah, I wanted Someday to feel more like an actual game, probably because 90's platformers are my main aesthetic.
Now that I think about it... yeah, the Purple Polka-Dot World is pretty lonely. All that keeps you company is a bunch of clay figures, and you can't get to any of them.
Most Someday NPCs don't have a canon name... well, they do. The pink Kirby-ish NPC is Bubbly, the tall colorful guy who gives the Blob effect is Kyung/Mr. 99, the Mado look-alike is Tsukitsuki, there's the Nice Guys, etc. The Grassland cat things I haven't decided, but I call them Shriekats. Shriek cats.
If you think about it and compare with the game's files, the OSTs are in the same order in-game and in the Music folder. 1 is the Doodle World's OST, 2 is the Question World, etc.
However, the 13th spot is empty. Why? Well, check the Music folder.