Star Ruler does pretty much what it says on the tin. And no, it's not a measuring device for celebrities. That'd be silly.
Where was I? Ah, yes. Star Ruler lets you command a mighty empire, create fleets and extend your reach throughout the galaxy; taking advantage of interstellar phenomena as you do so. However, I have to warn newcomers that the interface and GUI is patchy to say the least, resulting in some fairly basic control issues. For £2.50, however, you'll save a fair few quid if you're in the market and don't want to shell out for Endless Space yet.