Combine

The Combine, abbreviated as CMB and referred to as "Our Benefactors"[2] in propaganda, is the title of an immense and powerful interdimensional organization, composed of a massive variety of both allied and enslaved species. It is the Primary Antagonistic Force in Half-Life 2. The goal of the Combine is to build an interdimensional Empire known as the Universal Union and dominate the Multiverse.[3]

Introduction
The Combine empire sprawls across multiple parallel universes and is composed of an unknown number of sentient species. No one knows who is leading or managing the Combine, but it is known that aliens called Advisorsare doing all important administration between the Human race and the Combine.

The Combine manipulates species through a variety of means, including bioengineering and artificial implantation. The products of the Combine's re-engineering process are known as "synths", bio-mechanical organisms that serve a variety of functions within the empire. The Combine also uses their technology to create armies of super-soldiers, uniquely adapted for the particular environments of the conquered worlds. This process results in a highly mobile and adaptive military force which is able to respond to any threat and crush any opposition.

Vocal stress is placed on the first syllable. The name is pronounced COM-bine, as in Combine harvester, as opposed to the verb form com-BINE, as in "to join together or unite." Dr. Breen refers to the Combine Soldiersand Civil Protection as "The Transhuman Arm of the Combine Overwatch" [2] in Nova Prospekt, verifying that "Combine" is an accepted name of the empire, even by the empire itself.

It is unknown how many worlds the Combine has under its control; it is known that in addition to Earth, the Combine invaded the homeworld of the Nihilanth's species. The defeated Nihilanth escaped the onslaught and sought refuge in Xen.[4] It brought with it members of a number of enslaved or allied species, including theVortigaunts.[4][5]

Subsequent to the invasion of Nihilanth's unnamed homeworld, Earth became the Combine's most recently known annexation. It was acquired following Earth's surrender at the end of the Seven Hour War. Following the standard Combine process, members of Earth's dominant species were modified to form a new arm of the Combine military. In addition to forming the bulk of the Combine garrison on Earth, in-game dialogue suggests that units of the transhuman arm of Overwatch are also deployed across the Combine Empire in a "permanent off-world re-location". Assignment on other worlds is considered a horrible fate for Overwatch soldiers unfortunate enough to be stuck with it, and is often used as a punishment.[6]

Combine teleportation
Despite the highly advanced technical capabilities of the Combine, they appear to have a relatively limited grasp of teleportation technology. Dr. Mossman explains that while the Combine can teleport from one universe to another, they do not know how to teleport between different locations in the same universe. The teleportation method developed by Black Mesa enables same-universe translocation, and as a result the Combine is eager to obtain information on their teleportation technology. Dr. Mossman actually helps the Combine build a teleporter with such capabilities in Nova Prospekt, but it is destroyed during Alyx and Gordon's escape.

The Combine's method of teleportation appears to be highly inefficient compared to Black Mesa's equivalent; a large amount of power and massive pieces of machinery are required to perform teleportation, as seen at the end of Half-Life 2, where Dr. Breen attempts to escape from the Citadel using a Combine teleporter. This teleporter requires a dark fusion reactor to power it, while the teleporters designed by humans require relatively small amounts of power and very little machinery in comparison. Xen teleporters appear to require almost no machinery or energy of any kind.

While the physics of teleportation are poorly explained, it is known that Xenian teleporters use Xen as a "dimensional slingshot," bouncing off of one universe to another, and from one location in a certain universe to another in the same universe. Combine teleporters cannot do this, instead having to "tunnel" through dimensions to the target universe.