Steam News announces the OS X edition of XCOM: Enemy Unknown is now available. This is one of those SteamPlay dealies, so if you own the Windows edition, you already have this. Here's a reminder about the game: "XCOM: Enemy Unknown will place you in control of a secret paramilitary organization called XCOM. As the XCOM commander, you will defend against a terrifying global alien invasion by managing resources, advancing technologies, and overseeing combat strategies and individual unit tactics."