Computer games are used throughout our society. People play on the bus, at home and at work and we can see how computer games concern a number of areas in the society of today. Furthermore, we see an important industry emerging. The term "serious games" refers to games that engage the user, and contribute to the achievement of a defined purpose other than pure entertainment (whether or not the user is consciously aware of it). The additional purposes can, for example, be education, training, health care or marketing.