Mars

"Before humanity even knew what the stars were, we dreamed of visiting Mars. The bright red light in the sky has always held a particular fascination for our species, and now we can finally call it home.Mars was very much once like Earth, but since then the atmosphere has thinned, the water has been hidden away, and any life has long since disappeared. Begin by thickening the atmosphere and warming up the planet, and then you can set about re-introducing water, and eventually life."