Well, dont bother saying this is a copy of defend your castle... there is only one thing similar which is u are defending your castle, but with more enemys, spells, different system, and much more!
DUH! Defend your castle
Catch the heads before they hit the ground for points, but don`t drop more than five!
Knock down the snowmen with snowballs before time runs out.
Had a few to drink well then lets see how good your aim is.
Shoot down all the aliens!