If I were to somehow get ahold of a copy of Rhythm Doctor and modded in a new chapter of custom levels, these are the songs that I would consider using:
LH-1: Everything Black by Unlike Pluto
Rivulet Otter - Prolonged exposure to subzero temperatures has afflicted this slug-cat hybrid patient with chronic bouts of offbeat arrhythmia.
LH-2: For Me by Throttle
Analdis - N/A
LH-2N: Final Hope from ADOFAI
Analdis - Complications suffered as a result of previous tachycardial treatments have amplified the patient’s heartbeat to a dangerously high rate.
LH-3: Peer Gynt by cYsmix
Monk, Artificer - N/A
LH-X: No Hints Here! [EX] from ADOFAI
Rivulet Otter - An unexpected uptick in the patient’s beat rate has been detected. The patient had already been discharged and could not be contacted, leaving them at an elevated risk for cardiac arrest.
LH-XN: No Hints Here! [Original] from ADOFAI
Rivulet Otter - same description as day shift
The act ends with Rivulet catching the virus from somewhere in Middlesea, being discharged without it being detected, and returning to their globetrotting activities. Still, Rivulet’s metabolism isn’t very strong, so the virus wouldn’t be as much of a problem to them as the slugcats they’re spreading it to. I'm not very good at writing these descriptions . . .
Not as custom chapters, but you could publish custom levels (as long as the artist allows it; it gives you a list of music artists/publishers that accepts and denies thrit music to be put on levels)
Though IIRC there’s a clause about not putting music from other rhythm games (not sure if it also applies to ADOFAI since both are made by the same developer, but better be safe than sorry)
Because my Steam account is under Family View, I don’t have access to the Steam Workshop in the first place. From what I remember of the news log, the artist restrictions only apply to levels uploaded to the Steam Workshop.
Besides, even if the rules still apply to levels that aren’t published on Steam Workshop, I’m sure that I could find a way to pry them out of the files and broadcast them over RW-570.
And even if I can’t convert the file into an exportable format without going through copyright security, I could just put the music into the level post-export. The file extension implies that the levels are just rebranded ZIP files.
Also, Corkboard is down.