|"The Xenian Invasion"|
25 December 2014
Taking place in the "primary" timeline, this story follows on from "Epilogue" and features the return of the villainous Viktor Rascalov, who teams up with Nihilanth - the final boss from the original Half-Life (1998).
This episode also sees the first instance since the early City 17 Street episodes in which characters become "self aware" of their existence in a video game, as Viktor Rascalov uses the ability to change "maps" in order to get about the place.
- Nathan Johnson
- Alyx Vance
- Viktor Rascalov
- Gordon Freeman
- Combine Freeman
- Samantha Johnson
- The G-Man
- Wallace Breen
- Walter Bennett
- Issac Kleiner
- Eli Vance
Former crime lord Viktor Rascalov manages to make contact with Nihilanth and his Xenian army in the past and makes a deal to bring them to the present day and change the course of the Black Mesa Incident. Breaking into Walter Bennett's lab along with Combine Freeman, Viktor steals a Xenian crystal. Viktor spots Samantha Johnson (who is being looked after by Walter) and snatches her. Viktor and Freeman take Samantha to Isaac Kleiner's lab and use his teleporter to travel back in time to Black Mesa - just prior to when the Black Mesa Incident occurs.
Nathan Johnson and Alyx Vance travel back to Black Mesa in order to stop Viktor, who has knocked out Gordon Freeman and stolen his HEV suit in order to access the test chamber. Nathan and Alyx find Samantha trapped in Freeman's locker along with the man himself, and Nathan sends both Alyx and Samantha back to the future so he and Freeman can deal with Viktor.
Viktor causes the Black Mesa Incident and like in the original timeline aliens from the borderworld Xen begin invading. Viktor teleports himself to Nihilanth's chamber in order to link a gateway from the current time to 2014 earth.
Nathan and Freeman arrive on Xen and arrive at the Nihilanth's chamber. Nihilanth disintegrates Viktor and prepares to open the portal to present earth. Freeman sacrifices himself and blows up the Nihilanth's chamber, consuming both the creature and himself. Nathan is caught in a flash and later wakes up by the side of a road, and sees the destroyed Black Mesa Research Facility in the distance.
The portal was completely sealed, thus preventing the Combine from coming through and invading earth. Nathan decides to return back to Europe.
Meanwhile Wallace Breen and G-Man observe the destroyed facility and Breen is visibly annoyed. However G-Man assures him that everything will be fine.