Pretty good.
I like animation of main character. Graphics pretty neat, good variety of enemies. Neat menu options. FINALLY! Someone made buttons settings for Nintendo controllers!
Some things I don't like:
jump physics isn't good. You can't change attack direction during combo. And after any last attack there's pause and you can't move. Slow shield. And little impact. Animations themselves are good, but I prefer impact effects over good animation. Bump onto shield, slash enemies, getting hit, jump or land after jump. You barely can see when lava boss will strike after stun.
Very laggy. Stutters. My PC isn't even mid (Ryzen 5 5600x 3.7 GHz, Radeon RX 560 4Gb, 16 Gb DDR4 memory) , but game lags every 5 seconds. And yeah, I didn't see black screen. Game started immediately.
I said graphics is good and cute, but sometimes you can't see where is safe and where is hole (moon stage for example).
This is basically it. Looks like I wrote more negative than positive, but that's not like it. Game is good.
I even surprised. Good vtuber fan game outside of holo community is rare.
Ah, One thing. I don't like this font. Both in English and Russian. I hate it! Purely subjective!