They force 24 children out of 12 districts (1 girl and 1 boy, between ages 12-18) to participate in a game where you try to survive on your own for as long as possible. The rich districts, District 1, 2 & 3, train their whole lives to win the Hunger Games. Since they have all the opportunities to practice and become good fighters. In those districts, they usually volunteer to participate in the Hunger Games, because with all their practice, they usually win the Hunger Games.