Some feedback that you may want to consider, even though it's a WIP.
When you change sides, the animation is way too slow, it doesn't make sense to have it at that speed. It slows down gameplay and makes it very frustrating for the player. The animation should "obey" the players actions, not the opposite. At least not in this type of game.
Having a background image that size doesn't make sense either. It will hinder your performance in the long run.
I know the graphics are placeholder, but when you get down to actually making your own, make sure the style is consistent. For now, it is not and it makes the game just seem like a weird collage of found images.
The level design is pretty cool but it gets repetitive. The enemies that rush towards you are really cool and could be used to make some challenging segments.