By Darren Waters
Technology editor, BBC News website, in San Francisco
Computers the size of blood cells will create fully immersive virtual realities by 2033, leading inventor Ray Kurzweil has predicted.
Ray Kurzweil is a celebrated inventor and futurologist
Exponential growth in processing power and the shrinking of technology would see the development of microscopic computers, he said.
"We will see a billion-fold increase in the price-performance of computers in the next 25 years," he said.
"Virtual will compete with reality," he told the Game Developers Conference.
Mr Kurzweil said it was possible to accurately predict the growth and change in computing power by looking at how it had developed over the last 50 years.
"There will be a 100,000-fold shrinking of computer technology over the next 25 years," he said.
"Today you can put a pea-sized computer inside your brain, if you have Parkinson's disease and want to replace the biological neurons that were destroyed by the disease."
He said a billion-fold increase in computing performance and capability over the next 25 years coupled with the 100,000 fold shrinking, would lead to "blood cell-size devices... that can go inside our bodies and keep us healthy and inside our brain and expand our intelligence".
He said the blood cell computers would be able to "produce full immersion virtual reality from inside the nervous system".
People have more freedom in virtual worlds
He said the games industry had to be thinking about the future development of computing now.
"The games industry fits in well with the acceleration of progress; in no other industry do you feel that more than games."
Mr Kurzweil, who invented the flat bed scanner and text-to-speech synthesis, said the virtual world was a misnomer.
"In virtual worlds we do real romance, real learning, real business. Virtual reality is real reality."
He added: "Games are the cutting edge of what is happening - we are going to spend more of our time in virtual reality environments.
"Fully emergent games is really where we want to go. We will do most of our learning through these massively parallel interactions."
"Play is how we principally learn and principally create," he said.