Fun concept and nicely implemented the theme by connecting the zombies to spell the word. Not sure if all the letters needed spawn directy, but I had a lot of trouble finding an L for my Galaxy.
The game takes a LONG time to load, both at startup and upon finishing a word, there were times I thought it had completely frozen on me ;P
Encountered a bug in the 2nd word, where I accidentally pushed over the zombie with my starting letter and after that it would not let me get another zombie with the same letter.
Still, I shot zombies and had fun, so great job!