"Horizon Zero Dawn is an action role-playing game developed by Guerrilla Games and published by Sony Interactive Entertainment. The plot follows Aloy, a hunter who ventures through a postapocalyptic land ruled by robotic creatures, who sets out to uncover her past. The story is set in the 31st century, in a world where humans have regressed to primitive tribal societies as a result of some unspecified calamity. Their technologically advanced predecessors are vaguely remembered as the 'Old Ones.' Large robotic creatures known merely as 'machines' now dominate the Earth. For the most part, they peacefully coexist with humans, who occasionally hunt them for parts. However, a phenomenon known as the 'Derangement' has caused machines to become more aggressive towards humans, and larger and deadlier machines have begun to appear."
"Aloy wears a Focus, a small head piece that scans machines to determine their susceptibilities, identify their location, their level, and the nature of loot they will drop. One machine, the Stalker, can enable cloaking technology to avert the gaze of Aloy's Focus scan."
Horizon Zero Dawn's Wikipedia, retrieved June 11, 2019