This game has slight problems with feedback. I got a score for saved aliens in the end, but I have no idea what that meant. When is an alien saved?
Also, as touching the aliens depletes your health, and the alien movement is not dampened in any way, it seems like bumping one at the edge, and then waiting for the rest to slowly move off the screen is the optimal strategy, which is not that engaging.
I have to say that I still liked the feeling of forcing them all off screen in a big clump, and bumping the planets was fun.
For some reason I did not have sound, but expected music due to the title. But that might just be a technical problem.