Copy Kitty is an indie game (currently in Early Access on Steam) by Nuclear Strawberry (Azure and Raibys) that I chanced on almost two years and two versions ago. Given the gratuitous explosions and rainbows, this was very clearly the game for me.
The game is a platformer with shooting elements; the object of each stage is to destroy all of the target enemies. Boki has several maneuverability options, and can combine power-ups to create extra-flashy combo shots. In the interest of being interesting, I'm doing my best to go as quickly as possible.
If you're wondering why there's a blank space off to the right, that's where the annotations are supposed to be. Turn them on, although I guess you're out of luck if you're on mobile.
At this time, Vierne has 1,643 views for Copy Kitty spread across 4 videos. His channel published less than an hour of Copy Kitty content, roughly 3.46% of the content that Vierne has uploaded to YouTube.