As a gem hunter, go find all the gems stolen by monsters. There is a time limit on each stage so be sure to collect all of them before the time runs out.
The droids started attacking the remaining human resistance. They are controlled via main server unit deployed at the region of their attacks. Disable their server units and disarmed them all.
Build towers and defend your base against the waves of blood-thirsty incoming zombies. Earn points to upgrade your existing towers or add more new towers.
After the earth was nearly destroyed by an all-out global war, much of its land has become a wasted desert. You're one of the few survivors who must defend your settlement from hordes of mutants.