Great job!
The gravity was an interesting touch. Being slow really made you think before you moved. I really liked the story. Without giving the whole story away, all I will say is Poor George.
My one suggestion would be to show the beginning of the stage, where the rocket ship is descending, once and then allow the player to just spawn again without the rocket ship descending, however; the current mechanic in place really made me regret getting hit by an alien.