Very interesting concept. Gameplay is very smooth and visually amazing. Great job on the art work and movement mechanics. Music and sfx are also very well done. Some problems I discovered are, the player can hug the left wall and not take damage in first stage, hitboxes feel off,might be only me but didn't understand which else keys and can be used beside 'z' and 'space' , can be polished a little bit here and there.Overall the game is amazing.
Suggestions:
1.Making a game over screen when player dies.
2.Tutorial or a controls tab that shows keys and their uses.
3.A save system that saves the stages completed and if player dies, loads the stage which player failed.(If the game is supposed to be completed in one go then concept is good as it makes the game challenging.)