Intro reminded me of metroid, loved it. But really, it wasn't a metroidvania, there were like 2 branching paths, both are just different ways to the same place. Also, different sprite sizes tend to look odd, please just make a really big boss sprite instead of a small one which you upscale. Aside from that, the jump was a little finicky at times, but sound design, the player controller and the intro were all really nice.
But uhh, idk if you do have a save system on your non-web builds, but after dying on(what i assume to be) the final boss, and not being able to respawn close by, i just used that as an excuse to quit. Sorry if that means i missed a large portion of your game.