That was fun, got to the end of the demo. Couple things I noticed:
I only realised you could backdash at the end of the game, when I accidentally pressed the button. You could mention it.
Some enemies, such as bats, could be easily avoided by just keeping on walking. Maybe positionning them better or making them faster would make them more dangerous.
You take a big load of damage, and you can only recover it at save stations. Maybe I just suck, but I died a couple times.
I think I noticed the screen shaking out of nowhere a couple times? Or maybe that was just me.
Whip is great, but I noticed that it doesn't actually need to be completely deployed for it to do damage. In fact, you can deal damage at the first frame of the animation. It's easier for gameplay, but visually wise it's kinda weird.
On the positive now!
Damn that music. Seriously. That was so pleasant to hear.
The story is interesting, I'm wondering a lot about the characters (oh yes, a girl-only planet).
Animations and graphics were clean, great job!
It surely felt like a metroidvania, sometimes the entries forget about that.
Great game overall, I enjoyed myself!