You are a convicted hacker that returns on Earth after a very long unplanned journey, only to find everything changed.

Seems someone pushed the nuke button, then everyone else got frenzy pushing the same button. The Earth crumbled under the thermonuclear apocalypse and life under the good old Sun became suddenly complicated.

Everyone caring about his own life took a leap of faith and started to live in underground cities, where filtering systems provided clean air, constant temperatures and potable water.

Most people don't leave their underground cities, going outside is only for military, scientists, adventures or thrill seekers.
The separate dlc file is extra_dlc.asar and must be copied inside the EtherealDemo_0.6.3\resources folder near the other asar files.