Gordon has arrived at the Lambda Core sector, which consists of labs that had the scientists experimenting with teleportation. In a warehouse right before entering the main area of the Lambda complex, Gordon has a final encounter with the female Black Ops assassins.
Gordon then encounters several scientists at the Lambda entrance who were expecting his arrival. One of which informs him of the need to activate the Lambda's Core's power reactor. The powerful Gluon Gun can also be obtained from its designer and brought along for the journey ahead. Gordon then rides an elevator down to the main areas of the Lambda complex, which is infested by the aliens. Due to the damage to the facility, the only unblocked path left to reach the teleportation labs is to turn on a pair of water pumps that floods the Lambda Core's main reactor, which allows for Gordon to swim up the reactor to the teleportation labs.
Gordon next traverses the teleportation labs in order to reach the holed-up Lambda team. Once there, he's informed by one of the Lambda scientists of how the rocket he fired into space earlier ("On A Rail" chapter) ended up failing due to a powerful creature that's holding open the rifts between Earth and the Xen alien world. As a result, Gordon's given the mission to deal with said creature, which the scientists work a large teleport machine in the lab in order to open up a portal for Gordon to go through. Despite suddenly being attacked by Alien Controllers, the teleporter is successfully opened, and Gordon heads off to Xen.
This Chapter contains examples of:
- BFG: The "Egon" Gluon Gun can be taken at your leisure and functions as a super-machine-gun.
- Backpack Cannon: The weapon's method of portability.
- Death Ray: The weapon emits an energy beam that quickly chews through anyone standing in the way.
- Wave-Motion Gun: The visual effect is in the vein of this trope.
- Couldn't Find a Pen: A scientist is found dead having written the correct "2, 4, 7" sequence for navigating a Portal Network on the floor in his own blood.
- Non-Standard Game Over:
- During the section where you have to climb the main core using teleporters, entering the damaged teleporter 09 automatically kills you, even if you have god mode enabled.
- Also, waiting too long to enter the teleporter to Xen will result in a loss due to the teleport machine malfunctioning. It's also a loss if the scientist working the machine somehow dies before he manages to fully open the Xen teleport.
- Optional Party Member: There's 3 separate maps where Gordon stumbles across a security guard that can help Gordon around the next Lambda area.
- The first guard is for the areas surrounding the water pumps.
- The second guard is for the hallways that lead up to the Portal Network room.
- The third guard can help Gordon fight off Alien Controllers in the final teleporter room until the portal is open that sends Gordon off to Xen.
- Portal Network: Part of the level requires the player to traverse a 3-level puzzle consisting of 9 portals. Bottom floor has portals 1-3, middle floor has portals 4-6, and top floor has portals 7-9.
- Sidetrack Bonus:
- Before taking on the Portal Network puzzle, there's a nearby ladder that will take you down to a dead-end room. Along with the room having supplies, it's here that the dead scientist is found that left behind the portal sequence blood message
- The 1 through 9 Portal Network puzzle is this in a nutshell. The portal route to complete the level is taking portals 2, 4 and then 7. However, portals 1, 3, 5, or 8 all lead to side-areas for additional supplies before being sent back to start the portal puzzle again. Portals 6 and 9 are useless.
- Suspicious Video-Game Generosity: A Justified Trope as there's an armory kept handy for exploration teams due to a nearby super-portal to Xen.
