GTA: Bad Ass Builder
In the future, alien like insects would want to invade our planet for its resources. We need to take care of our own or the entire alien race would just take it if we aren't ready to fight for it. Resources are not as it was before, so everyone wants to get a hold of it. The alien creature would keep on coming and we need to fight as we are still alive. They won't take any hostage and so we need to be ruthless. Your ammo is unlimited if you have the basic guns, but those guns that you can get from enemies is not unlimited.