What makes it unique is that, while a single-player game, it will populate your world with the creatures of others, lending it a multiplayer aspect.   The creature creator itself was released earlier this summer, and I spent some time playing with it.  I don’t know how practical in-game any of my critters will prove, nor do I know how any of the ones I downloaded to my creator will be.  It’s nifty though how easily you can take someone else’s creature into your game.   The intent is to have creature-casts as well as buddy (and ignore) lists.   It launches in one week, and I’m excited to see how it plays out!