Sci-Fi fans should seriously consider dropping £2.56 on this sweet little BundleStars offering. It contains... deep breath... Sword of the Stars II Enhanced Edition, Project Freedom, Weird Worlds: Return to Infinite Space, SpaceChem, SpaceChem: 63 Corvi DLC (add-on), Really Big Sky, Planets Under Attack, Data Jammers: FastForward and Ion Assault.
Again: £2.56. This is a seriously good deal, especially since you'll get Steam codes for the lot.