I'll answer the question by copy/pasting what I wrote on the review page:
"My mind is slipping. I am following murderous orders on my telephone answering machine. I think... maybe it's in my head. Did I really kill all those people? Did I really survive? I feel uneasy. Nauseated. The room won't hold still. There's static in my brain. Colors seem to crawl around in my head. Hideous hues of Pepto-bismal pink, convenient store neon orange, and baby poop green. I sniff hard through my nostrils and fight back the urge to vomit. The only way to stop thinking about the killing is to kill more. In the killing there's no time for remorse, no time for pondering long term consequences, there is only action. My eyes dart around every corner, door, and exit. My muscles twinge in reflex. My brain plans its moves: Shoot. Sprint. Pounce. Stab. Hide. Fire. Run. As I take life, mine is reaffirmed. I am alive. I'm bound tight like a rubber band pulled on both ends, about to snap. But I can only think a few steps ahead. I don't know what lies ahead other than danger. I must be vigilant. I must be aggressive. And when it is all over, I will think I must be sick. Horribly, horribly sick. But there's not time to think about what's wrong with me now. I'm already through the door. The trigger has already been pulled. I'm already in the chase. Guns are blazing. I'm in it. There's no turning back.
Hotline Miami is that. It's not just a game, it's a psychological experience that emerges out of the ugliness of the graphics, the head-bending visual effects, the trippiness of the music, the andrenaline fueled gameplay, the tension before opening a door, the horror and quiet of walking out of a room where you have murdered every living soul and their bloodied bodies are in piles. To break it down into gameplay, graphics, sound, control doesn't seem to do it justice. It is killer's instinct, confusion, evil, guilt. It is terror. Surprising calm. It is a disoriented nightmare. It is succumbing to that urge at night to just swerve into the headlights. It is waking up in someone else's blood. It is all your fault "