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.
Help the space rebellions to drive the evil spacelord out of the Minoria system. Deploy, defend and attack their solar systems to take control of the galaxy.
Aliens have infiltrated the naval command ship. You are the captain and you'll go down with your ship. The question is how many aliens will you take down with you?
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.