Gameplay
Through parts of Half-Life 2 and almost the entirety of its sequels, Episode One and Episode Two, Alyx serves as an ally to the player, assisting in combat and allowing the player to progress by opening doors and removing other obstacles. Alyx's health quickly regenerates, allowing her to recover quickly and survive a fair amount of punishment. As long as the player does not deliberately avoid helping Alyx, it is difficult for her to be killed. Notably, while Gordon requires the use of the special HEV suit for protection, power, and other abilities, Alyx appears to need no such enhancement.
In Episode One, where Alyx's role as a companion is expanded upon, her artificial intelligence (AI) was designed specifically for co-operative play to complement the player's abilities. The developers described Alyx's programming for Episode One as a "personality code" as opposed to an "AI code", emphasizing the attention they gave to create a unique and believable companion. In addition, she was specially programmed to avoid performing too many mechanical or repetitive actions, such as repeating lines of dialogue or performing certain routines in combat situations. Examples of this co-operative gameplay include combat in underground levels, where the player can use their flashlight to help Alyx spot and kill oncoming enemies, thereby conserving their own ammunition. Similarly, Alyx will often take up strategic positions and provide covering fire to keep the player safe while they travel to a certain area or perform certain actions.
Alyx's primary weapon in the games is a unique automatic pistol resembling a machine pistol in operation and a Glock-series pistol in appearance. Alyx also wields a shotgun identical to the one available to the player in the later part of Episode One. She also uses the mounted Overwatch sniper rifles at various points in both Episode One and Episode Two. In Episode Two she can also fire while Gordon is driving a car if he is moving slowly enough.
Read more about this topic: Alyx Vance