I press a buzzer on a dingy apartment door, and a single pulsing eye appears on the intercom screen. My voice comes out frail, disappointed, all age and regret. "KPD," says the visitor, meaning Krakow Police Department. "I need to talk to you for a moment." The voice that responds is incoherent, rambling, paranoid. I find myself wondering if it's even real.

That's not the kind of question I often ask myself in videogames, but Observer is something special. The first-person experience by Polish studio Bloober Team features one of the most convincing realities I've seen in some time—and the devs build it for the express purpose of breaking it apart. Normally, I happily let games go where they want to without stressing over the integrity of the world they inhabit. After all, it's not real; the difference between hallucination and objectivity isn't an essential one. But Observer, a cyberpunk meditation on the frailty of perception and the tenuous bonds that tie people together, made me question my own eyes.

In the game, you play a titular "observer," a type of futuristic detective who gathers information by plugging into the neural implants of victims. You begin in a patrol car, receiving an unexpected, abrupt phone call from your son. The game moves to an apartment complex in the slums. The complex goes on lockdown for unknown reasons not long after you arrive, trapping you inside with all the tenants. What follows feels like Die Hard if it had been written by Philip K. Dick and directed by David Cronenberg, where the only way to escape is to solve an existential mystery about the nature of reality.

What's really important here isn't the plot, but the presentation. As you jack into the implants of the dead or dying to determine what's going on and where your son might be, reality gets fuzzy. The world is already unstable, dotted with holographic augmented-reality displays that warp space with a mixture of advertisements and propaganda—but once you jack in, everything changes.

The memories of a dying person aren't pleasant. In harrowing segments full of fragmented hallucinations and broken spaces, Observer pulls you through entire life stories as they flash through collapsing minds. I found myself inside a prison cell with a convict enduring withdrawal, only to jump to his apartment, where he lies dying. As I move through it, it loops and fractures, and I'm back in prison, walking down an endless hallway. In another memorable segment, I'm in a cubicle farm that slowly morphs from a metaphorical labyrinth into a literal one; piles of retro-style computers and servers jut from the walls, glistening as if alive.

After experiences like that, nothing quite feels real anymore. And when hallucinations from the mental world start seeping into the real one, the entire landscape of the game finds itself in unstable territory. Is any of this real? Whose hallucinations are these? Bloober Team sells these questions with a stunning devotion to space and presentation. They're not new ideas, and the story Observer tells isn't original, but space and time shift before your eyes in uncanny and unsettling ways. Technology and flesh blend in creepy ways. The apartment complex's navigable corridors and rooms turn into genuinely impossible mental landscapes with a stunning, unsettling clarity.

Obsever sells the sense that you don't know what's coming next, and it invests its environments with such dense detail that I found myself genuinely invested in knowing what parts of my experiences could be mapped to an objective reality—if any. This is Observer's best trick: I wanted to understand this place even as it fell apart around me.

The game, on PC and Xbox, isn't likely to reach a wide audience, and many who do play it might be turned off by its rough edges. It tosses unnecessary and tedious stealth segments into its cyberpunk haunted house for no compelling reason, and Rutger Hauer's central vocal performance is awkward and wooden (though it does sell the sense of a deeply disengaged, alienated noir protagonist). Several of its individual pieces don't work. But it flows beautifully as a whole.

Late in the game, you're offered a choice. You can jack into the brain of one more victim, enter one more broken world, or you can move on. Hesitating might cause you to miss key information, but who knows what will happen if you forge ahead? Each psychic journey is a violation of objective reality, and one too many could break your observer. Could break everything.

The brilliance of Observer lies in this simple detail: I hesitated, because I was genuinely afraid of what might happen. Any game that accomplishes that is a game worth playing.