The Citadel. Built in 1986 by a lunatic and left undiscovered, decomposing for 30 long years. You are its first victim.
The Earth's looking a bit Grim, but so would you after 5000 years and countless alien invasions! Grab your spacesuit (the air's not so great any more) and go for an adventure in what is still a beautiful world.
Master the swivel by guiding spheeres through Circulate's 100 puzzle levels.