Fable II is set in a fantasy land with incredible detail and, like many stand-out new games, the ability to make your own moral decisions.
Fantasy allows the writer to create a completely new world, but in reality, all good fantasy is a commentary on modern society. Fable II has taken this aspect of the genre and used it to make the game laugh out loud funny, mocking a time and place far enough away that we can simply laugh at how much has changed (fair maidens will try to rush the hero into marriage, for example) -- or, more importantly, how much remains the same -- for instance, one immoral choice the hero can make is to buy up shops just to raise prices and take a profit.
The hero is ultimately on a quest for vengeance, which means that each quest results in a moral conundrum. In one mission, a ghost requests that you go through an elaborate scheme to break the heart of a young girl, his ex-lover, simply for revenge. Whether you follow his instructions or not is up to you, though most gamers admit that taking the moral low-road results in a much more entertaining game.
One complaint is that relationships between characters are lacking. However, many players have become emotionally attached to their loyal dog companion who is at your side throughout the game.
Check out Fable II for a fun fantasy / action game that uses it's genres in a very smart way.