I like this so far!
All levels are playable, and interesting too, they make you think.
Things I'd suggest are sound (if pico supports that, i've never used the engine), and some kind of indication when you've completed all the levels as I accidentally started playing from the beginning again.
It would also be nice if the viewport could be in the centre of the screen (as it's where your eyes naturally fall)
Great concept though, keep going!