A Focus is a small device worn by human users that serves as a multipurpose neural interface. This device is responsive to the user's gestures and voice, and displays a visual 3D interface visible only to them, aiding in the operation of machinery and technology alike, as well as in communications.
The device looks like small silver triangle, approximately an inch long from base to tip, that attaches to the user's temple (presumably lightly embedding itself so as to not fall off) close to the ear. It is extremely durable and can remain operational for hundreds of years, as evidenced by Aloy's Focus being left in a cave exposed to the elements for nearly 1000 years and losing no known functionality.
The use of Focus devices dates back to the days of the Old Ones, who commonly used them to control their technology. Despite being a fairly common device in ancient times, its use among tribesmen is very rare, as many of these villagers deem the technology of the Old Ones as something taboo and even forbidden.
The Focus is somehow linked to the technology present in machines as well, as Aloy can scan machines with it, revealing information about them such as components and behavior, and in some cases, the three-dimensional interface will extend and adapt to machines to facilitate some processes.
Below is a list of the known functions of the Focus:
- Making the structures of nearby machines visible through obstructions, similar to an X-ray.
- Scanning machines and registering their information, including weaknesses, in the Machine Catalogue in the Notebook. This briefly leaves them and their weak points highlighted.
- Optionally places a marker to allow for tracking a machine outside of scanning mode.
- Optionally places a trail on the ground indicating a machine's patrol route.
- Revealing tracks or evidence left behind by humans or machines.