place. Freeman battles Combine Overwatch to infiltrate the Citadel but is captured and taken to Breen. With suppressing the revolution failing, Breen flees to the Citadel's trans-dimensional teleporter to escape. Freeman destroys the teleporter's reactor before Breen can flee, causing a large explosion that destroys the top of the Citadel. In Episode One, the destruction of the teleporter has isolated Combine forces on Earth, and its primary reactor has begun to melt down. This forces Gordon Freeman and Alyx Vance to journey back into the critically damaged Citadel to stabilize its reactor while the city's inhabitants are evacuated. The Combine forces, however, instead attempt to accelerate the meltdown in order to contact their native dimension for reinforcements. After Alyx acquires an encrypted copy of the message to be sent, Overwatch forces desperately attempt to stop the pair from escaping the city, spurred on by Combine Advisors. As the pair escape on a train at the end of the game, the Citadel detonates and destroys City 17. Episode Two opens with Alyx and Freeman learning a superportal to the Combine dimension has formed in the Citadel's place, progressing to a stage where the Combine can send reinforcements. They also discover that Alyx's encrypted data from the Citadel can reverse the portal, and so traverse the countryside to deliver the packet to another resistance headquarters at White Forest. As they progress, Combine Advisors have escaped the Citadel's destruction, and remaining Combine forces are regrouping, albeit under attacks by Vortigaunts. Aware of the resistance's plans to close the superportal, the Combine attack White Forest in force, but are repelled. The superportal is destroyed after the resistance launch a satellite containing the appropriate data. Two Advisors attack Freeman, Alyx and Eli Vance, and kill Eli before being driven off. The Combine are again the primary antagonist in the prequel Half-Life: Alyx, taking place between Half-Life and Half-Life 2. The game focuses on the efforts of Alyx Vance, her father Eli, and fellow resistance member Russell, as they attempt to infiltrate a massive Combine vault, believing it possesses a weapon that they could use to weaken the Combine occupation on Earth. After navigating through various quarantined zones of City 17 and rescuing Eli, they discover that the vault is constructed not to hold a weapon, but as a prison, which they deduce to be holding Gordon Freeman. Alyx infiltrates the Vault and learns that it