Violent scenes in computer games are supposed to densensitise us, but when Lucy Prebble had to help a man dying of tuberculosis she was prepared

I finished The Walking Dead the same day I started The Last of Us. Both apocalyptic zombie games (or infected, if you're going to be precise), they have similarities. They're both good enough for me to have got soaked in their worlds and their blood.

The following day I was walking down the street and I heard a woman shrieking. She was on a mobile phone with her back to me. As this was in the real world, my assumption was that she was getting good news. I thought exam results perhaps, or a relative's pregnancy. But her screaming went on longer than would be socially acceptable. I slowed down.

The woman kept screaming.

Spores of information floated about. Her husband. The door. Neighbours came out. "Have you opened the door?" "Has she been burgled?" Lots of conversation, none of it building a picture. A woman called the police. A woman was on the phone to the police. The other woman wouldn't stop screaming.

Eventually it was clear her husband was in the house, ill in some way. I assumed she couldn't get in. I went to the door. Not locked. A man was holding it shut. "We're waiting for the ambulance." I went to a woman with her phone. "I won't go in there," she said. "The ambulance people are asking me to go in." "I'll do it," I said. "Do you want to take the phone?" I took the phone. There was an ambulance man on the phone. He told me to go to the door. I pushed open the door. The door stopped against something. A body. Then I saw.

There was blood everywhere. There was blood on the floor. There was blood on the walls. There was blood all over the face and throat and body of a man. He was lying, crooked on the carpet. There was blood all over white tissues scattered. There was blood on a roll of toilet paper, finger marks of blood. He had been trying to get out. Blood. Everywhere.

Everything around me looked like one of my games. I couldn't go in the room. "You must go in the room," phone man said. I think to myself, if this was a game, you would go in the room. The Last of Us has me constantly creeping into dingy, bloody holes and being heroic. The Walking Dead forces you to make moral choices which infect your narrative, which judge you. And so, and forgive me but it's true, by imagining I was in a game, I walked into the room.

The man was covered in blood and vomit. His eyes were open staring upwards. They were like a doll's eyes. They were like glass. The pupils were set. His face was contorted, mouth open. I could not look despite all the monsters and frothing and undead I've fought. I have never seen anything so big be so still. Everything vibrates, even just a little bit. But this didn't move. He didn't move. He was cut out of time. Everything in me said get out of the room. The man on the phone told me to go closer.

I kept pretending I was in a game.

How have I never seen a dead body before? In real life, I mean. He asks me to do chest compressions on the man. He is cold. I try. I take instruction. I put the phone down. Clear his airway. I can't. I can't. You can. Blood and vomit. Come on. Come on. He is cold. I can't touch him. Yes you can. But what if he comes back as a zombie? I am genuinely afraid now my protective mechanism is exploring its own conclusion. My brain tidies that stupidity up. I can't look at his face. This is what the protagonist has to do. I put my hands on his chest. Oh God. Oh God.

Eventually, they came.

The man was dead. He died of tuberculosis. He coughed up blood until he didn't have enough blood.

Now as I write down what happened I am beginning to forget how it really was. I remember the story of what happened, not what happened. It didn't have an order in time or a logical progression like this, it was just a thing with an image and a feeling. Now what I remember is my memory. For weeks afterwards, I played it over. And over it, I played. Every single zombie, or infected, or attacker seemed like a person to me now, a backstory, an individual and a trauma. Every injury felt profound. Every detail seemed sharp with adrenaline. The event in my life made the game more real and emotional, as the events in the games had made my real experience more false and manageable.

I used to scoff at the simplicity of equating onscreen violence with its real-world equivalent. But now there is no doubt in my mind that gaming can desensitise to death and gore. I'm just not sure that's a bad thing.

My mind has been busy, privately, with its own desensitising and placating. It's been filing, controlling, fighting and protecting. Getting me to the next level. That's its job. Today for the first time since that happened, I bashed a zombie's brain out with a spiky metal pole and felt nothing. That's not true. I felt the mild elation and giggly cringe of executing a well-designed violent manoeuvre in a video game. But nothing else. That's better.