First Impressions: Really clean graphics, UI - looks professional (the buttons etc). Quite challenging to know what to do initially. Once I pressed E I think I then understood that one state allows to bounce, while the other holds you in position.
Constructive (honest) feedback: I personally found it a bit difficult to make the transition between jumping and floating still in order to land on platforms. I would have liked maybe a little animation of delay when you die to restarting the game - its very non-dramatic when you die when it just instantly restarts and you teleport back to the beginning!!