Sleeping Golem

Many centuries ago there was war between two giant forces, one of them was an oppressive empire and one was the union of resisting forces. The empire used powerful machines to conquer nations, these machines are self sufficient, they don't tire, they don't sleep, they're merciless and can't be destroyed. To stop the empire the union used powerful emp bombs. These bombs were powerful enough to change the surface of the world. The explosion changed the landscape of the continents and made the climate colder. The explosion left a powerful radiation that wiped out all the technology that man had before. Because of these changes the survivors have to live in underground cities and wait until the world becomes warmer. After many centuries, the empire that used to have big structures are now covered in thick forests. The remaining machines are still intact and soon when the radiation's gone, they will rise up again to guard the ruins of the empire.

-PSCS3