This was impressive for your first game, nice work. I thought the controls were easy to learn and the animation was good too. The music was a nice addition to the game, and the achievements made the game pretty addictive. This game focuses on a somehwat overused concept of fall down and avoid, but I like how you put a story in the game and your own unique twist on it.
The rocks started going in the same place every time in the beginning, so it was more like memorization than reflexes. The speed of the rocks definately made the game challenging, but when some rocks are moving quickly in such a confined space, it becomes are real hassle to be entertained by the challenge. Anyway, good work on this game, I'm looking forward to playing the games you'll make in the future. Keep up the great work!