Nice music and graphics, I especially liked the slime graphics :)

A few comments:

The level-design was a bit unfair at times, scrolling you into situations that were practically unwinnable. This was exacerbated by the limited lives.

I occasionally got stuck on the air (looked like the wall-climbing animation)

Interesting idea, it can be a bit unfair because you're not sure what's below you, personally I would give the player infinite lives, but I think the gameplay overall is fun and challenging and the graphics are smooth.