The world suffers from oil crisis and you have to defend the last desert oil-base from the incoming enemies and armored vehicles. Earn experience points to get new weapons and don't forget to use power supplies dropped by allied aircraft.
Blow apart big waves of zombies using an array of guns and hired buddies to fight by your side. Purchase bigger and better guns and hire assistance with big firepower to give those hoards of zombies a good spanking, keeping them away of your territory.
You are the commander of a space battle station. Below you, on the planet's surface, enemies are trying to capture deadly missile silos. Don't let them seize these silos. Protect them at all costs!
