Stellaris, the sprawling and much-expanded 4X space strategy game by Paradox, is free to try out from now until Sunday, May 12th. If you like it, you can snap it up for cheap. The game has now been out for three years, and while it may have been considered a little bare-bones at launch, a trio of major expansions (and some smaller DLC) plus some huge free patches have turned it into a 4X favourite. As well as managing a sprawling space empire, it has a bit of personality to it, with major and minor story arcs cropping up in the vein of Crusader Kings. See the anniversary trailer below.