Innovations in Half-Life 2: Episode Two
Half-Life 2: Episode Two begins with Alyx helping Freeman to get out of the wreckage of the train carriage that had fallen from the destroyed bridge.
Now the heroes can take a look at the consequences of the explosion of the Citadel that wiped City 17 out from the face of the Earth. Although the suppression field has been removed and the Combine Advisors are being hastily evacuated and Dr. Breen has run away, it soon transpires that this is not the end of the Combine’s rule on the Earth and the agonizing Citadel has been sacrificed to create a powerful impulse capable of carrying an information packet. With this information the Combine is planning to open a new portal and send reinforcements.
The player learns that Alyx has managed to copy the transmission which, besides everything else, contains information about the location of the Combine’s home world as well as data necessary to create a new portal controlled from there. The module with this information must be safely delivered to the resistance base to prevent a second invasion of the Combine that would lead to an ultimate defeat of the human race.
Although the hero and his allies have delivered a sensitive blow to the Combine, the enemy is still strong enough to renew the hunt after Gordon and Alyx. Soon after the hero is left alone, Alyx gets wounded by a Combine Guard. The wounds are serious and the friendly vortigaunts with all their superhuman abilities can hardly keep Alyx’ mutilated body alive.
At the underground base Freeman forces back an attack of antlions and then goes into their lair to find the healing essence for Alyx. After that the two heroes have to move to the resistance base where a rocket is being prepared for launch. According to the plan, the rocket will be able to close the portal and avert the new invasion.
Episode Two offers more different levels than Episode One : abandoned mines and underground antlion tunnels are interleaved with vast open spaces.