The Combine is not just an alien race — it’s a vast interdimensional empire that absorbs and assimilates everything in its path. Known for its brutal control over Earth in Half-Life 2, the Combine's roots lie far beyond our world, in a web of universes connected by teleportation technology and conquest.

The Combine originated from a different dimension entirely, where they evolved or constructed a regime based on control, surveillance, and bioengineering. They do not rely on one form or species — instead, they conquer intelligent lifeforms and reshape them into tools of their empire. This includes turning conquered beings into soldiers, machines, and even infrastructure components. As such, the Combine we see is a hybrid of many races, all stripped of their identity and made to serve a central overlord.
Their arrival on Earth was triggered by the events at Black Mesa. When Gordon Freeman opened a resonance cascade during an experiment, it created a rift between dimensions and allowed hostile alien lifeforms from Xen to enter Earth. These events attracted the attention of the Combine, who viewed Earth as a valuable resource-rich planet and a weak target.
Their invasion was swift and overwhelming. Known as the "Seven Hour War," Earth's governments surrendered in less than a day, unable to fight off the Combine's superior technology and transdimensional forces. In the aftermath, a puppet administrator, Wallace Breen, negotiated Earth’s surrender and became the figurehead of Combine control.
The Combine’s rule is characterized by oppression and manipulation. They drain Earth’s resources, suppress human reproduction, and use biomechanical implants to transform humans into their own enforcers — the transhuman Overwatch. Their structures, such as the Citadel, are not just buildings but machines of war and control, designed to suppress resistance and channel power back to their empire.
The Combine represents a nightmare of unchecked power — an empire without identity, fueled by assimilation and devoid of mercy. Their origins may remain mysterious, but their presence is unmistakable: a chilling vision of what happens when science, conquest, and control are pushed beyond the limits of humanity.