9. The Borealis
You might remember, in the final discussions with Eli Vance at the end of HL: Episode 2, that Gordons next stop in his mysterious quest to save mankind (although, Ive a sneaking suspicion that the entire Multiverse is in fact under threat from the Combine) is the Borealis; a research ship of Black Mesas rival company Aperture Science, which mysteriously vanished from its dry-dock only to be rediscovered in the Arctic. If you played Portal 2, you might also remember discovering the Borealis empty dry-dock as you searched for escape in Aperture Sciences research facility. Valve seem to be drawing our gaze toward the Borealis, hinting that it might contain the last hope for the Half Life universe. In their race to beat Black Mesa, Aperture Science have clearly been messing with portal technology way beyond their comprehension (I think the Portal games and of course the sudden disappearance of an entire research ship prove that) and I cant wait to find out what fresh hell awaits for us aboard the ghost ship Borealis. So come one Valve, get a wriggle on will you?