I really enjoyed this game (I just love Metroidvanias). I think it would've been cool if you hid secrets everywhere, as it encourages exploration. I felt that the camera was too low, I think I would've preferred a higher camera with the option to look down. The game was also missing audio. Audio can add a lot to a game, so having anything at all would've probably been nice. Finally, I had trouble distinguishing many of the areas, causing me to go in a few loops around the world every time I needed to find the next object.
This is a great game, nicely done!