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"Somewhere in that sequence, they would have had to establish a connection with the far side. What you have there young lady, is the specific contact code for the Combine Overworld."
Arne Magnusson[src]

The Combine Overworld is apparently the Combine's original homeworld. It can be assumed that the Overworld is the primary world from which the Combine launch their invasions of other worlds from, though this has not been confirmed. The Overworld may also simply be another world conquered by the Combine, and not the actual homeworld of the Combine organization.



The Citadel model ("portalspire.mdl") used in the map.

Very little is known about this world, as it has never been directly mentioned in any of the Half-Life games, except for a vague outburst by Arne Magnusson in the Episode Two chapter To The White Forest.

The strange, alien world which is widely assumed to be the Combine Overworld makes its first appearance at the very end of Half-Life 2's final chapter, Dark Energy. The primary method of communication between Earth and the Overworld appears to be the Citadel's dark energy reactor, an immense and powerful machine which the Combine can use to open a rift between the worlds. As Gordon attempts to sabotage Dr. Breen's escape through the reactor's portal, the player can catch a glimpse of the Overworld on the other side; a striking orange skyline of what appears to be many Citadel-like structures can be observed. The two Combine Gunships which attack Gordon can be seen emerging from that location as well, hinting that the Overworld is home to the Combine's Synth army.

The Combine Overworld's climate seems to be different from that of Earth. From what can seen through the portal, the orange sky appears gaseous and intangible - strange clouds and even what look like stars can be seen, bearing an appearance similar to that of Xen. The Advisor wears a small black cup over its snout, suggesting it cannot breathe Earth's air, and all transhuman Overwatch forces have completely airtight outfits, even though the wearers are modified humans on Earth; this suggests that although they do not need it on Earth, it could be useful in other locations such as worlds with a different atmosphere (although the outfits do not feature oxygen tanks). The Overwatch Voice also tells several times to Overwatch troops that "mission failure will result in permanent off-world assignment", hinting any Overwatch unit is meant to be able to operate in other Combine-controlled worlds, the Overworld itself or other unknown Combine colonies. This suggests that the Combine Overworld does not support oxygen or nitrogen, the primary gases of Earth's atmosphere. Before Breen attempts to escape through the portal at the end of Half-Life 2, he says to an Advisor that he cannot survive in the environment beyond the portal; the Advisor (presumably) answers he could do so with a new 'host body', which Breen hesitantly accepts.

Behind the scenes

In the original final showdown conversation at Breen's office, Breen was to mention the "Aleph universe" as the universe Eli and Alyx were to be sent;[1] this might be referring to the Combine Overworld. Interestingly, "Aleph" is the name of the main protagonist of Prospero, Valve's first game project, that the team probably recycled for it.[2] "Aleph" is also the name of the first letter in the Hebrew, Arabic, and Persian alphabet, which makes sense as the homeworld is the "first" world.


Overworld through portal

The in-game appearance of the Combine Overworld in Half-life 2.

  • The Citadels seen through the portal are very similar to an early version of the City 17 Citadel used in cut propaganda posters.

List of appearances


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