So I'm not quite sure what happened, but somehow in the middle of the second boss battle I got kicked back to the previous page...? I'm using Opera; presumably there's a 'go back to the previous page' key combo that's easy to make by accident whilst playing the game :x
Hardly your fault, but still an oof.
Concept is fun, I love the verticality to the levels, and I love the enemy variety. As for criticisms...
It took an embarrassing amount of time to realise I could doublejump.
The air attacks are very finicky, making the air enemies near impossible to hit at times. The up attack in general could do with some forgiveness with its controls, or maybe having 'aim up' and 'jump' be separate inputs. At least you gave the flying enemies no collision damage; that was a good call.
Platforming was fun, but on the second level getting to the station, it could really have done with more clarity on where it is and isn't safe to fall.