The machine civilization of Xi (pronounced ZEE) was a society of robots, artificial intelligences and cyborgs that appeared across the globe in many of Earth's realities (called worldlines) previous to the fusion of those realities into Gamma Terra by the catastrophe known as the Big Mistake in 2012. When it was all over, Xi and two other major powers: the Thuu Marth shadow government of Area 52 and the Empire of Ishtar were the only nations able to consolodate their resources from across the merged planet to reassert their power. During the 150 years that followed, known as the collapse, the three powers declared war upon each other and tore Gamma Terra into ruins. Now all that remains of Xi are rusted factoriums, much sought after supertechnology known as Omega Tech, and the various descendants of the nations survivors: drones, robots, nanotech, A.I. systems and cybernetic organisms.
Not much can be said with certainty about the machine civilizations. They seem to have been the most diverse between worldlines, accepting each other as kindred despite a variety of different origins and histories. They certainly share strong ties with machine supremicist movements such as the Machinists also known as the Created. It seems the Artificial Intelligences, pure software, stood at the top of their organization and unaugmented humans stood at the very bottom. It can be assumed that the drive to incorporate more and more technology into oneself had become the major motive of citizens of Xi.