Wow, just wow.
I love your art.
And your game mechanics.
I can only mention a few problems:
BALANCING : All levels were too easy compared to the boss fight. I think you could have added a few more challenging levels before the boss fight.
MUSIC : Music was great but I don't think it fits the boss fight level. That is just my opinion.
STORY : At the beginning the NPC said trust no one but there was no explanation or something to tell you what is going on?!
PAUSE MENU : There is none :(
Overall your game was awesome, I was sad that how soon it ended :(
I think you should release a full game out of this, it has a lot of potentials. Your game can be the next Hollow Knight.
9/10
Good luck.