The writing, graphics, and music all blend together very well. Very creative to tie your poem in with the game mechanics - using writing like that is not easy. The shooting mechanic is also fun to play around with, and I like how you gradually introduce different game mechanics to keep the game interesting.
One thing I would have liked to see more audio feedback for the shooting and for when enemies die. Since the later levels have lots of enemies, they tend to group up, and I think it'd be a lot more satisfying to mow them all down if there was a death sound effect. I also think the later levels should be a little more forgiving, as you only have one life and the enemies ramp up in numbers quickly,
Very enjoyable experience overall, and I'm glad I came across this game. Great job!