This gets a full 15 stars rating from me. I love it. It's a basic simple idea that gets extended and explored in many exciting and interesting ways.
The enemies are vaired and challenging and they fit perfectly with each other throughout the levels.
Also this game presents a strange mix of 1D and 2D that I don't think I have ever seen before.
Only thing to say is that it has some technical inconsistencies, for example, if you play some levels starting with the space button down it should give the same output, instead sometimes you get hit by a ghost and other times you pass that ghost without problems.
Also I suggest to "block" the input when the player dies, meaning that you should have to release the spacebar and press it again, so if you die while holding it you don't get moving right away on the next respawn.
Awesome job, please make more levels and release a full paid version