[quote=Sep]
You do realize that the antagonists of this roleplay are guys called Kiith who take over multiple Universes?Transdimensional Combine aren't going to be too much off a problem for them.
[/quote]

Its multi-universal empire. They are known as the universal union and they control an unknown but likely large number of universes by using their advanced dark energy teleportation devices to zip into different universes and grab them for their empire. Also, we don't know what invaded Earth. Its implied by Breen, (especially if you consider its function to serve as a link, a bit like constructing a dock) and a line from hl2 raising the bar that the citadel appeared after the surrender (The war lasted seven hours, the citadel, according to raising the bar, replaced entire blocks of the city overnight, which thus might be after the seven hour war) The majority of the invasion force has already left too, what we see in hl2 is just an occupation force, and its possible they used other types of more deadly synths (we see some in the game we never fight, and the hunters didnt turn up till white forest making it possible that the combine had reserves of forces that we know nothing about) hence why they try to call for reinforcements and Vance comments the Resistance wouldn't last seven minutes.

Thus, a second trans universe empire could be a massive problem...