On FOOTPRINT ISLAND,
the ecological cost of the things you consume must come out of the land you have on the island. You must set aside land to grow your food, collect your water, generate your energy, and compensate for the resources it takes to produce the things you want to have.

So in the game you can see very clearly how your life makes a footprint on the earth - and also how your lifestyle choices affect the size of your ecological footprint.