Link: Food Force
Force force is a game made by the UN World Food Programme that gives players a taste of what it would be like to carry out a humanitarian relief program. Players fly a helicopter to find starving people, make food, buy food, drop food, drive trucks through rough terrain, and then assist the community afterwards.
The game is very simple. Even children can understand how to play it without too much hassle. It is not a serious computer competitive game like Quake or Unreal but more of an educational game. It is completely free to download although at about 200 MB be sure to have a fast Internet connection. It would be a great idea for teachers to let their students play this game for educational purposes.