Observer is a psychological horror video game played from a first-person perspective. The player controls Daniel Lazarski, a Krakówian detective of the Observers police unit. He can hack people's brain implants with a device known as the Dream Eater, for interrogation purposes. Equipped with augmented vision split into Electromagnetic Vision—which scans for electronic devices—and Bio Vision—which scans for biological evidence he is able to analyse and highlight certain objects in his environment. Objects can be interacted with and examined, while dialogue trees are used for speaking with non-player characters. Nanophage cards, patient records, radio-controlled cars and roses serve as collectibles. A mini-game called With Fire and Sword: Spiders is accessed through computer terminals, which can also be used to read documents.