Jane McGonigal is a computer-game designer and researcher at the Institute of the Future in Palo Alto, California. She has just published a book, Reality Is Broken , which details how we can "power up" our real lives using the lessons learned from computer games. You can read my review of the book here .
Why do you think computer games are so important?
There are two things. One is the sheer number of people playing games and the amount of time they are spending on them. There are half a billion people on the planet who spend an hour a day playing games and they are reaching almost 100 per cent of people under 18.
Then there is a staggering amount of research suggesting that the games we play can have a positive impact on our lives. We're not just escaping from life by playing but "powering up" our real lives.
Of all the ways that games make us happy, which is the most valuable?
Eustress -- positive stress, which is physiologically and biochemically the same as negative stress. The adrenalin gets going and the attention is focused, yet when we choose to be in that state, we think of it not as anxiety or pressure but as excitement and motivation. What is really great about this state is that, when you start to tap into those positive emotions, they can spill over into real life.
What is the biggest challenge facing those who want to make the world better through games?
There are people who are very dismissive of games and gamers, who feel that gamers are throwing their lives away. There is a lot of strong emotion around that, which can be hard to break through. And then the crucial thing is to motivate the world's best game designers and developers to spend some of their time working on games that improve our lives and solve real-world problems. I would like to see 10 per cent of a major company's portfolio dedicated to that.
Tell me about game-based learning and the Quest to Learn school in New York.
This is a school that has been designed in collaboration with educational researchers as well as extremely experienced educators and game designers. They wanted to make a school that would tap into the self-motivation and collaboration that games provoke in young people. It wasn't about putting tonnes of technology in the classrooms but about deeply understanding the psychology and the social aspects of gaming.
What about SuperBetter -- an alternate-reality game you designed to help you beat the concussion you'd suffered from a head injury?
There I was, writing about how games channel our positive emotions and build positive relationships better than anything else, and I was feeling more pessimistic and depressed than I had ever been. It was a good opportunity for me to say: "If I really believe this, then a game should help me through this." And seeing how effective that was definitely made me feel more like an evangelist for this kind of game -- because it literally saved my life.
Do you think the focus has moved from computer games to alternate-reality games?
I think there's a balance. More traditional games innovate because they are so focused. They are more engaging, create better cognitive emotion and more co-operation. For alternate-reality games, which have a second goal of improving lives or solving real-world problems, we need to be able to work with the innovation that is happening in the commercial gaming industry in order to achieve those goals.
In Reality Is Broken, you briefly mention those who want to ruin games -- "griefers". Are they a worry?
With every game we've designed [at the Institute for the Future in Palo Alto, California], we have had people show up who are opposed to the idea. They disagree with the goals or they disagree with the idea that gamers can accomplish anything. In our games, you have maybe a dozen griefers at most, in a group of 20,000. The more wholehearted players you have, the harder it is for griefers to get any traction.
What would be a good game to try if you have never played before?
If you want to see a game that's important right now, which over a hundred million people are playing, Facebook's CityVille is a great one. It belongs to a totally new genre -- social games.
Jane McGonigal's Reality Is Broken: Why Games Make Us Better and How They Can Change the World  is published by Jonathan Cape (£12.99). You can follow Jane on Twitter here: @avantgame .