A crash course in changing the world.
My idea is fairly simple: make a computer game that involves a miniature of the earth.
The setting should resemble the earth before the starting of the industrial revolution. The players will be asked to participate in the possible outcomes of the world, which means they get to see how much water will be spent to do certain activities or jobs. The game interface will be a world map, on the side there will be a bar that represents the population and another bar representing the water resource that is left.
The population will keep growing and the water resource will be depleted in time. To develop a technology will help people live better, but meanwhile polllute or otherwise just spend more water. As the players make progress in the game, the landscape will change. For example, the rivers will be dried up, and the Antartica will split up, etc.