The most excellent people at Stardock have released a
demo of their 4X space conquest game. The demo is good for about 144 turns or so and allows you to play a quick game with the Terran race. You can also read our review of the game
here.
DO NOT DOWNLOAD THIS DEMO.
Why you ask? Because downloading the demo will lead you to purchasing this most excellent game. The game will then keep you up way past your bedtime as you try to sneak in extra turns because those bastard Iconians are trying to eliminate you from the universe. Sure they've got a slight edge in economic but they can't defend you planets against the full power of the Drengin empire. Then you'll spend the next day drinking highly caffeinated beverages to stay awake and thinking about how nice it's going to be to when you invade their last planet and exterminate their race from the universe.
Not that I would know anything about that *yawn*