The Ancient Civilization were a race of proud, magically and technologically adept beings that destroyed themselves by overuse of Nightmare Lights, causing the periods of magical flux and possibly unleashing Shadow Creatures which helped in bringing its ruin.
In it's beginning, the Ancients were a small race of insect-like beings which scavenged for food, and suffered due to the small amount of food and resources, and living in fear. Later, they discovered Nightmare Fuel, which they soon mass-produce, shrouding them in dark, enviable power. The Ancients then evolve into totally different appearance (most likely due to the excess amount of Nightmare Fuel), and expand into a massive, militaristic, technologic superpower. They become rich with Thulecite and Nightmare Fuel.
It was this civilization that produced the Clockwork Monsters, which can be found swarming the military biome, suggesting they used them as mechanical soldiers. Maxwell found them and adapted them for his own use. It seems that they were also religious as the Ancient Pseudoscience Station is referred to by Maxwell as a place at which they may have worshiped. Some of the magical items prototyped from the station show that they were very skilled in the use of magic, as they used staves capable of such abilities as summoning miniature-stars, and short ranged teleportation, as well as creating armor capable of producing short lived force fields. The ancients also appear to have amassed a large wealth of the now rare material, Thulecite, as many of their artifacts have either been constructed entirely of it, adorned with it, or contain trace amounts of the material.
The ancients also seems to have a powerful Military, as their remnants are littered with Clockwork remains. The ancients were also protected by a powerful guardian, but even its great strength helped little against the shadow creatures, and it was transformed into the beast that can be found in the deep labyrinths of the ruins. After the once great race had ended, all that remains is their technology, Relics, and the aftermath of their nightmare abuse, the Nightmare Cycle.
- The ancients must have used electrical power in some form, as their Relics can drop Frazzled Wires when destroyed.
- The ancients have a few similarities to the Dwemer from The Elder Scrolls series, due to the fact they had their own types of stone or metal used, were technologically advanced and left only their work.
- While little can be confirmed about their appearance, the appearance of the Mage Statue reveals that the ancients may have been arthropodic in structure, with a slightly knobbly shell on their backs resembling that of a pill bug. It may be important to note that in the Nightmare Cycle, spikes can be seen extended on both the Head and Mage Statues, showing that they may have been able to extend spikes from their bodies maybe if angered or in self-defense.