A Valve employee , who works in game development, surprised his girlfriend by proposing to her during a demonstration of his company's virtual reality hardware in Seattle.
Kelly Tortorice was testing out the new HTC Vive headset, developed in collaboration with Valve, when a virtual diamond ring appeared on the screen before her eyes.
When he took out his headset, Chandler Murch was holding a real ring in the place where the virtual one had been.
Ms Tortorice revealed on Facebook that she finally accepted her boyfriend's proposal.
While some tech journalists have claimed the marriage proposal was a publicity stunt to promote the new device, which is expected to be released next year, Ms Tortorice said it was a "hilarious but fun surprise".
"So there I was, just another typical day... on a sunken ship deck, fixing robots, drawing 3D fires, hiking in the Alps, and then suddenly, a virtual engagement ring started floating before my eyes," Kelly wrote on her personal Facebook page.
"Chandler told me to grab it. Then he told me to take off the set of headphones I was wearing, and he was really there, kneeling in front of me, with a real ring in his hands."
"It wasn't fantastic anymore. But I didn't say, 'Yes.' I said, 'Of course I'll marry you!'"
And he added: "I love you, and I can't wait for the life that awaits us from here on out."
