Hi!
I like the concept of pushing the enemies off, pretty fun!
I also like how you can basically fly with CTRL, goofy but fun.
What I would focus on is better explaining of what you need to do. It's nice that you added a tutorial, but it should explain how to progress, it's too vague.
The music is also not the best. I'd recommend using a LONGER track, which is loopable. Will make playing 100x more fun.
The technical issues (such as the player disappearing sometimes) are a smaller problem, you can always fix some small bugs :D
Anyway, good luck with the game!
By the way, it would be awesome if you checked out my game as well, thanks!