Defend your base! Use your magnetic ship to pick up chunks of junk and drop them on advancing enemies. Absorb junk into your ship and base to upgrade them and assure your victory.
Survive as long as possible by building the most efficient line of defense. Eliminate the bad guys from attacking your home base. There are also several different game modes available.
Prepare your defense against the oncoming waves of creeps. Don't let them complete the path. Do that by building your base that consists of defense towers along the way.
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.