"Officially they call themselves the Universal Union," Gordon says bitterly. "They're a race of dimensional raiders who move from one universe to another via dimensional portals. They conquer the worlds they reach and start modifying the native lifeforms into appropriate cyber-modded tools for whatever campaigns they might happen to have in mind. Synths, they call them- different species, different capabilities, but it's all the same. When they got to Earth they imposed some kind of energy field that stopped the human reproductive cycle and turned off our reproductive urges so that there wouldn't be any more humans born until they'd decided whether we were worth adding to the arsenal, or should just be allowed to go extinct. It's been sixteen years since a human child was born, and everywhere you go, there's Combine Overwatch soldiers with more chips in their head than a damn Pringles factory."