In a solar system at the fringes of a galaxy far, far away is a planet currently friendly to the sustained existence of life. This planet is inhabited by relatively intelligent bipeds (they call themselves “humans”) who have developed habits that threaten the survival of the species.
Most of the time those “humans” just go about their business without thinking much about the consequences of their actions. Some humans have begun to take advantage of the other humans’ indifference and damage the environment.
These “Evil Forces” have shaped human civilization to a large extent and have become an accepted part of the human community as a result. Just like in real life the Evil Forces are not easily recognized as such. They are at work during the Times of Darkness and destroy the elements on this planet that make survival for humans possible, one by one.
Fortunately, some concerned humans have recognized this danger and meet occasionally at a “Global Conference” to attempt to identify the Evil Forces and vote to eliminate them. Humanity wins if the Evil Forces can be eliminated before they eliminate what is necessary to survive. If the Evil Forces are able to eradicate everything “good” on the planet they win.
Obviously in real life it is not that easy, but this is just a game.