Page "Combine (Half-Life)" Paragraph 6

Little is revealed of the Combine's rule outside of Earth, but dialogue in Half-Life 2 states that they control worlds in different dimensions and inhabited by a range of species.

The Combine occupation of Earth, however, is shown to be a brutal police state.

In City 17, a generic Eastern European city, Civil Protection units are seen frequently, often conducting random searches of apartment blocks, interrogating human citizens and engaging in random police brutality.

The military Overwatch forces of the Combine are shown attacking human resistance bases in an effort to further solidify their control.

The citizens themselves are all clad in blue uniforms and live in designated apartment blocks.

Citizens are shown to be moved around to different cities or locales at the Combine's will, using passenger trains.

Vortigaunts, alien creatures from the original Half-Life, are also shown to have been enslaved, and are observed in various jobs such as janitors.

According to Half-Life 2: Raising the Bar, the Combine are draining the Earth's oceans, minerals and resources, to be used on other Combine worlds.