One of the givens in an MMORPG is that each player must choose a faction, usually right at character creation. In Warcraft, you are either part of the Horde or the Alliance. Alliance players are always human, dwarf or elves, and Horde players are always orcs, trolls, goblins, and so forth. This, of course, all dates back to Tolkien and a perhaps a dualistic view of the world that was made for a very convincing good guys/bad guys story. Gollum may have been the one character in those stories pulled in both directions, a study of the light and dark, Jekyll and Hyde.
If George R.R. Martin has done one thing for the fantasy genre in Game of Thrones, he has blown apart the trope. The “evil” Lannisters certainly have their more admirable members in Tyrion and Ser Mormont, and the “honorable” Starks certainly have their overly black and white view of the world in Ned, and of course many characters who are somewhere in-between. It’s a much more complicated world, which in many ways is very realistic and satisfying, but perhaps a bit less comforting. It’s good to know who the enemy is.