Haydee

Haydee is a female cyborg with a voluptous body and prosthetic arms. She wears a snug plastic plate on her upper body and a thong leotard while her lower body is bare except for high heels. With the exception of a blue display on the back that shows her vital signs, the cyborg's head is devoid of features such as eyes and a mouth, rendering her unable to speak or convey her emotions in a conventional manner.

Haydee is a cybernetically modified/manufactured human female, controlled by the Player, that works her way through the game by solving puzzles, exploring the environment and defending against any hostile enemies in her way. Haydee has several options available to her as to how exactly she accomplishes these, including deduction/brute force against puzzles, calculated/blind exploration or evasion/destruction of enemies. However, Haydee may be forced to use any of these methods depending on the circumstances; whether it be a puzzle that results in death if wrongly attempted, easily missed-opportunities that would be extremely beneficial to her or simply having limited ammunition.

Haydee herself is an extremely capable individual, being able to use any item given to her immediately without error, use firearms with perfect accuracy and even having unlimited endurance for physical activity. Her dependence on the player however means these abilities are worth nothing in bad hands, but gives experienced ones unhindered control.

Non-Player Haydee Units

Early on in the game, it is made clear that the Player controls one of many Haydees, as there are several other inactive units identical to Haydee scattered around the area, implying Haydee is just one of an entire model/line of manufactured products.

The purpose of each Haydee unit is to work their way through the facility and replace its master with itself, allowing them to reconfigure it as they wish. However, another option is initially presented to each Haydee unit; escaping the facility altogether, although this is actually unachievable and results in the units seemingly eventually dying of natural causes instead.

As hinted at by the beginning console text and demonstrated by the control ending, each Haydee unit is designated by a specific iteration. The Player-controlled Haydee's iteration is AB16-800B-58AB-E832. If a Haydee unit fails to replace the master, either by attempting to escape the facility or being killed, the last iteration quad will increase by 1; as seen by the Player-controlled Haydee's designation ending in E832, while the next Haydee's ends in E833 as seen in the Deadlock and Escape endings. If E832 instead becomes a master, the 2nd to last iteration quad increases instead for the next unit, signifying a new cycle; in the Control ending, the new Haydee's designation is AB16-800B-58AC-0000.