By level 5 there is really not much rock left :( What's the highest level that it's reasonably possible to get to? Perhaps the difficulty curve of the levels should be slowed down a bit.
The gameplay is really nice, definitely challenging! Perhaps the pointer to the target should start a bit earlier, it's tricky to look at the mini-map and the main game at the same time.
Just make sure you don't fall
Ok, this is a very fun game!