I don't know if it's a true creation of Steven Moffat or.. just a fan who likes VERY MUCH Doctor Who, enough to create a whole new alphabet from another planet. :3
Doctor Who: the estrella Beast is part one of the 60th-anniversary specials that featured the return of David Tennant as the 14th doctor. The episode is loaded with easter eggs and references to Donna's time as a companion, and break them all down