Phi Brain: Kami no Puzzle - Orpheus Order-hen

Shows based on Vocaloid originals or involving utaites/producers who are/have been active on Nico Nico Douga (extended to YouTube for newer gens).
While not its own genre, these compositions tend to have a recognisable feel to them.
(Updating as I come across songs, you can poke me to add stuff as well :D)

2nd stack for post-2020 anime debuts: https://myanimelist.net/stacks/26372

Actual Vocaloids:
GUMI ~ Joshikousei no Mudazukai / Agukaru: Play with Ibaraki-hen (cv: Megumi Nakajima)
IA ~ Recorder to Randoseru Mi☆ (cv: Lia)
Miku ~ Akikan / Watamote / Yami Shibai / Black Rock Shooter / Kemurikusa / ALFA-X / Aware! Meisaku / Petit Seka (cv: Saki Fujita)
MEIKA Hime & Mikoto ~ Hakata Mentai! Pirikarako-chan (cv: Kotori Koiwai)
Luka ~ Copihan (cv: Yuu Asakawa)
Meaw (possibly) ~ Honto ni Atta! Reibai Sensei
Go! Go! 575
Zunda Horizon

Prioritising first appearances/multiple artists bc of 50 limit. For composer entries, the singer is only listed if they're
At some point, I'd have been super hyped for any show with a Vocaloid producer but come late 2010s they've been popping up everywhere :')

*List is roughly sorted by anime based on Vocaloid songs > Male utaites > Female utaites > Producers

This list contains some Anime series about characters in gaming setting whether video game, gambling or even tabletop game. If you are into this type of Anime, then you're in the right stack.

For help with challenge: https://myanimelist.net/forum/?topicid=2022043&show=0