While HealthSeeker is focused on helping and educating people with Diabetes (it's sponsored by the Diabetes Hands Foundation) the introductory video stresses that anyone can benefit from the healthy changes encouraged by the game. As in The Life Game, gaining experience points in Healthseeker involves accepting and performing "missions" that involve simple changes in your everyday life -- such as using vegetable oil instead of butter in cooking, for instance.
The social element comes in via "kudos" that you can send to friends to encourage them on their missions or "challenges" that you can issue to urge friends to become healthier. Ideally, the social pressure will make you more likely to stick with the changes than if you were just "playing" alone. Of course, there's always the risk you'll just lie about your success online instead of admitting your failure to your friends. Stay strong, health warrior. Stay strong!