Xen

Xen is a parallel dimension discovered by the Soviet Union in the mid-20th century that has become the source of an existential threat to Earth and the wider multiverse. Xen is the native home realm of the aggressive, technologically-advanced alien species known as the Combine, who have used their ability to traverse dimensional boundaries to conquer and subjugate worlds across the cosmos.

The Combine Homeworld

Xen is believed to be an ancient, highly unstable parallel universe containing strange physics, exotic matter, and bizarre alien ecosystems. It is the original home of the Combine, a highly organized, militaristic species adapted to survive in Xen's extreme environment.

The Combine possess advanced interdimensional travel capabilities that allow them to traverse the boundaries between Xen and other dimensions, including our own. They have used this power to systematically invade and conquer untold numbers of worlds, assimilating their populations and resources into the Combine's vast galactic empire.

Soviet Experiments at Black Mesa

In the 1970s, the Soviet government established the top-secret Black Mesa Research Facility in eastern Siberia to study the nature of Xen and the Combine. Through extensive and reckless experimentation, the Soviets hoped to harness the power of interdimensional travel for their own strategic advantage.

The Soviet scientists at Black Mesa were able to make significant breakthroughs in understanding the structure of Xen and developing technology to safely traverse the dimensional boundary. However, they gravely underestimated the risks involved and the true nature of the Combine threat.

The Resonance Cascade

In 1998, a cataclysmic "Resonance Cascade" event caused by the Soviets' experiments at Black Mesa tore open a large, unstable rift between Earth and Xen. This allowed the Combine forces, sensing a vulnerable new world to conquer, to rapidly invade and occupy the weakened Soviet Union.

The Combine's assault was overwhelming, and they were able to quickly subdue most of the Eurasian landmass under their authoritarian rule. Only a fragmented but determined human resistance movement has managed to slow the Combine's total domination of the planet so far.

The Ongoing Struggle

Humanity now faces an existential threat from the Combine, who seek to fully assimilate Earth into their interdimensional empire. The destruction of the Black Mesa facility was only the first step in the Combine's plans, as they work to consolidate control over the rift to Xen and bring the full force of their military might to bear.

The scattered human resistance, led by former Soviet commander Alexei Kovalev, is desperately trying to find a way to close the rift to Xen and sever the Combine's access to our dimension. Preventing the Combine from spreading their dominion to other worlds in the multiverse has become a critical priority for the survival of humanity.

However, the Combine's vast resources, advanced technology, and ruthless methods have made them an extremely formidable foe. The ultimate fate of Earth and the entire multiverse hangs in the balance as this desperate struggle continues.