The Cthonians were an alien race that featured in the game Battlezone.
The ancient Cthonian race existed hundreds of years ago in the Sol system on a planet between Mars and Jupiter that was known as Icarus. However, interfighting amongst themselves led to the destruction of their world which led to the creation of the asteroid belt that now decorates that part of the system. During the course of their history, the Cthonians involved themselves among developing Humanity which led to the Greeks worshipping them as gods.
At the time, however, civil war had erupted between the Hadean Crown and the Olympian Council the result of which was the destruction of the species which in turn led to the downfall of the Greek civilization as their deities had vanished. The leader of the council was Paternus who guided his people with wisdom and knowledge which led them to seek a better way of life through science. Some of these secrets were shared with Humanity until their homeworld was destroyed in the civil war.