Oh, this is Good!
This one is really fluid and feels like a solid metroidvania. You've done superb work on it.
The music is very enjoyable and sets the atmosphere well, the sound design is excellent, and the movement controls feel good.
General bugs/issues:
* I got the triple sword upgrade, but can still only swing once. Did I manage to get an upgrade out of order? In that case, wouldn't it make sense to just increase the number of attacks by one?
* Not being able to attack while in the air feels very limiting.
* A visual indication of an enemy taking damage would help indicate if you need to hit again or just missed.
* The floor-shooter enemies seem to attack from off screen. It would be nice if they only could start their attack while on screen, and and would cancel out of it if off screen. Otherwise I feel unable to dodge the attack.
* Backtracking takes a long time, so more interconnectivity might be good. Or Fast Travel between save points.
I think I found the boss, and it killed me pretty fast. :P I'll need to explore some more to find other things.
Once again, great work!