?15 minutes to save the world?: a terrifying VR journey into the nuclear bunker

It became clear that things had gone terribly awry on this particular day when I saw that the most moderate option on the desk in front of me involved killing at least five million people.

I could kill up to 45 million if I chose the more comprehensive of the alternatives laid out on three pieces of paper, but it was hard to focus on the details because there were people shouting at me through my earpiece and from the screens in front of me.

I was experiencing what a US president would have to do in the event of a nuclear crisis: make a decision that would end many millions of lives - and quite possibly life on the planet - with incomplete information and in less than 15 minutes.

In the real world, I was in a meeting room in a Washington hotel, but with virtual reality goggles strapped on. I was sitting behind the president's desk in the Oval Office. The television news was on and there was a report about Russian troop movements, but the volume was muted and someone was telling me the national security adviser was running late for our meeting.

I tried to shift my focus back to the news but a few seconds later a siren went off and a bald man in a uniform and dark glasses appeared from the door to my left.

"Mr President, we have a national emergency," a woman's voice said. "Please follow the military officer right away."

The bald officer ushered me into a wood-paneled lift which had been concealed behind a wall, and we began our descent.