The original chapter name was Down and Out. After an attempted interception by Alien Controllers, the scientists activate the teleport and he is teleported to Xen. To prepare for what lies ahead, Gordon arms himself and collects the Long Jump Module.

Gordon learns that he must kill it to prevent the Xen aliens from completely taking over. The handful of surviving personnel, who have held themselves up in a small stronghold, inform Gordon that the satellite he launched was not able to reverse the effects of the Resonance Cascade because an immensely powerful being on the other side was keeping the portal between the worlds open. Gordon navigates through the Lambda Core, facing numerous assaults from the Xen forces, now the primary enemy after the evacuation of the HECU.ДЄfter much struggle, Gordon finally reaches what is left of the science team where he discovers that the Lambda Complex is where the teleportation technology that allowed scientists to travel to Xen was developed. He is informed that he must flood the reactor chambers in order to access the core, and that a team of scientists is waiting for him at the tip of the reactor. Gordon arrives at the Lambda Complex, but instead of the science team, he finds that the majority of the complex is now overrun by hostile creatures.

The teleport chamber in the Lambda Complex. Gordon starts a trek across Black Mesa to reach them. Back underground, Gordon learns from a scientist that the surviving members of the Lambda Team, set up in the Lambda Complex at the other end of the facility, may be able to close the dimensional rift. He finds the area completely under the military control and in the middle of a mortar bombardment, forcing him to retreat back into the complex. Gordon continues battling through hostile forces, both alien and human, until eventually reaching the surface. While attempting to join up with them, Gordon witnesses a soldier killing an innocent scientist, revealing to him that the Hazardous Environment Combat Unit is there not only to eliminate the alien threat but also everyone else connected to the project. He learns that the soldiers rumored to be coming on a rescue mission have already arrived. This chapter finds Gordon passing through various storage and staging areas, continuing his hunt for a way to the surface. Since the tram system is too damaged to function, Gordon must cross Sector B's Coolant Reserve Facility in order to find a way out. Gordon also occasionally witnesses the G-Man, watching him from out-of-reach places. Most are simply reacting naturally to their new surroundings, but even more hostile are the creatures glimpsed earlier, known as Vortigaunts, who seem to attack with a single-minded intent to kill. Black Mesa has suffered massive structural damage, and aliens from Xen begin randomly teleporting in all around the facility. Eli requests that Gordon try to reach the surface in order to find help. He manages to reach his colleague, Eli Vance, who informs him that all communication outside Black Mesa has been lost. Waking up back in Black Mesa, Gordon makes his way out of the Test Chamber. This chapter introduces the player to weapons, combat, and environmental hazards, among other things. This chapter details Gordon's efforts to reach the surface to get help in the aftermath of the Resonance Cascade.

Blast pit half life