Combine

The Combine is the powerful multidimensional empire which serves as the primary antagonistic force from the 2004 video game Half-Life 2, and the subsequent episodes developed by Valve. The Combine consist of organic, synthetic, and heavily mechanized elements. It was later that invaded and conquered planet Earth, and wiped out most of human civilization during the Seven Hour War in the year 2162.

Origins
TBA

Early Life
However, it is unknown when the Combine existed in 500 BC.

Current Era
In the year 2039 of the 21st century, their homeworld was discovered by the Aperture Scientists and NASA scientists with an intergalactic technology detector, which is 100,000 km light-years away from the Milky Way Galaxy. Next year, the Combine arrive at City 17 on planet Earth and create the enormous structure located in the epicenter of City 17, The Citadel, which serves as the main base of operations and the headquarters of the Combine, from which they govern the Earth. Two years later, the outsides of the Citadel were blocked by the R.O.R.G. Drone Shields, which were not letting the Combine aerial forces leave the Citadel. 119 years later, the Combine Super Synths were built by the Combine to give it more superior power, then destroy the R.O.R.G. Drone Shields and break free for the Combine ground troops and aerial forces to obliterate the small inhabitants of City 17, then build their own civilizations on City 17. Next year, the Combine builds 30 of the Combine Superportal Generators to activate them and fly up in the air to open the superportals around the world. Then the Combine aerial forces come down from the superportals to conquer and invade Earth, enslave humanity. 25 years later, Earth is now entirely ruled by the Combine.