Clever concept, pretty fun game. It could be really good if you had more levels that made better / more involved use of the gameplay mechanics. Right now it feels a bit like an extended tutorial.
Excellent game! The gameplay was really good, made you think, especially with the reversal in the second half. However, I have to say I didn't like the "story" captions between levels - too maudlin and cliche with no characters to back it up. Otherwise, though, good stuff.