I just beat the Game through all 4 victories. When going for the "Re-Build Whole City" win, please remember that the more soldiers you use, the more zombies you kill. I sent in 24 soldiers on an 'Overrun' and cleared in one attack.
Game is so addictive. The music is a tease though. It makes you think "Oh look... this game is peaceful, relaxing, and fun" yet right now... my mind is going "IM GOING TO KILL THIS GAME!"