Build towers to defend the town center and upgrade them to more advanced tower types. These towers are capable of protecting more with powerful weapons. It applies to fire, ice and lighting magic towers.
Monsters must protect San Francisco or even the world from these evil aliens. Place your monsters around the map to defeat the incoming waves of aliens.
Taken from Hero's popular series into new genres and beyond with 7 enemy types, over 11 unique tower paths and tower merging allowing for mega towers and mega-mega towers.