Well, first of all, I like the UI a lot, though I think I'd probably like it more on my actual phone instead of my pc.
The monsters are cute, but I'd like to be able to do more with them.
Soundtrack is obviously fantastic.
Overall, congrats on getting this out, It's early so most criticisms I could throw at it aren't really relevant yet.
Though there's an extra kernel of humor there for the idea of making a gacha-idle game since most actual Gacha games are basically just idle games anyway.