Oppai Muse is exactly what you'd expect if you combined a rhythm game with unapologetic fan service—it’s bold, bouncy, and brazenly over-the-top.

I managed to get 100% of the achievements in about 1.5 hours, with quite a few restarts.
I don’t have good reflexes, and I don’t blame RNG.
I’ve seen other reviews claiming to achieve 100% in 20 minutes, as well as reviews stating that some achievements are bugged and won’t unlock. Take that into consideration however you like.

The game itself only requires your mouse.
Despite what the game description says, I wouldn’t really consider it a rhythm game.

You collect hearts that spray onto the screen, with each heart giving you a score point.
Additionally, there are multipliers to collect and red squares to avoid, all while a song plays in the background that somewhat matches the heart-spraying pattern.
The songs aren't great but decent, in my opinion, and I found myself vibing along.

After each successful level, you unlock a new girl and get a few customizations, such as filter effects, clothes on/off or the option to add text. It’s nice to have, but I don’t really see a purpose for it. Probably intended for making screenshots or displays, but for this purpose, the customizations and artworks aren’t particularly impressive.

The current highest discount was 40% and for that I can recommend it.