Really nice to see a Metroid Prime-inspired entry!
The game's looking and sounding nice. I liked the environments as they provided a few explorable paths and took advantage of the third dimension. It was also nice to hear the saw from a distance and the sound getting louder when approaching. The rocks could have used a stronger effect when you break them with the missiles, but there's otherwise plenty of feedback and particles to underline your actions.
But the experience was overall a bit frustrating and I was sad not to finish it.
First, the Escape key does not pause the game, it closes it without confirmation... which I thankfully learned early in my playthrough.
The breakable rocks can be hard to see, which can be a nice way to encourage looking closely at the environment, but because I took some time to find them, I wasted all my missiles experimenting on other parts of the environment, to the point I couldn't progress any further. I had to kill myself using the "abyss rooms" to refill my ammo. Speaking of those rooms, I didn't understand them at first, so I died without knowing why. A better feedback on those rooms and a way to always refill your ammo would already go a long way to improve the experience.
The enemies are pretty cool, though placing the flowers near the entrances, to the player's back, feels a bit cheap. But they don't do much damage, so it's no big deal.
I gave up in the platforming section. I was often surprised by the jump distance considering its height. I often thought "no way I can make that jump" when I could. But falling kills you instantly and send you back to the last powerup you gained, which was quite a few rooms from there. The second time it happened I couldn't bring myself to retry, which is a shame because I was really intrigued by where the game was going. If you could respawn the player on the last platform with a chunk of health missing, it would make it way more palatable.
In conclusion I found it very promising, and if those issues can be fixed it has the potential to be a really good 3D metroidvania! ;)