Hmmm i don't think vocaloid would fit as a genre, since you can have "rock vocaloid songs", "pop"... uh you got the point right? And pretty much tagging as vocaloid would be enought.
Vocaloid is an instrument, not a genre of music. To be fair, video games and anime are far more popular both within and outside of osu!, so having categories for them makes more sense. All Vocaloid maps should have the word vocaloid in tags anyway.
