Aenigma

Set in the year 4XXX, humanity lives disconnected inside underground megastructures to escape the threat of the ever-expanding silicon-based lifeforms.

After the nuclear fallout from the third war, the planet's surface was rendered unhabitable. Silicon-based life were created to serve as slaves being tasked with building underground structures for shelter inside of the planet's mantle. When the slaves grew in number, they slaughtered the carbons who claimed ownership over them. The silicons burrowed deeper into the mantle to create their own sanctuary. This marked the start of a long war between the carbons and the silicons. As time went by, the silicons grew more in power and in technology, while the carbons stagnated. The mighty has fallen. This was now... The Silicon Age.