Instead of building towers and defending against hordes of monsters, play the opposite as an evil mage that builds his army from the ground up to dominate the lands.
Zombies and ghosts are invading! Defend the local neighborhoods by building an array of towers to shoot at them and open gates to redirect their hungry minds to places of choice.
As a united military forces of the whole planet, hold the line at all the directions from the green meadows of Europe and snowy Siberia to the burned cities. Use all the resources to protect your world from aliens.
