Loved the game and would be thrilled to see more of it!
After a couple complete playthroughs, trying to maximize the size of my city before launching my spaceship, I still couldn't really figure out what the walls were for? I found that the arrow towers were more than enough to defend my island.
I was really liked the song at the end. I wish that the game would calculate a score or something based on how long it took for me to launch my spaceship and how many people I had on it.