I must agree with the other commentators. The idea is really great.
Sadly, you didn't do the graphics yourself. But the asset pack you picked out still fits.
Also the music you have chosen fits perfectly. The music is not just one loop, but several tracks, so you won't get bored.
Short to the controls: apart from the constantly changing keys, jumping and running works great. However, sometimes you get stuck in platforms that you should be able to get through. I also got stuck in the wall a few times. And you slide down on slopes.
I liked the level design especially in the third level. At least I think it was the third level. Here I was forced to actually use both directional keys and couldn't just press "Right" and "Jump".
Don't take the criticism too hard. I just wanted to mention a few things that I noticed. All in all it was fun