Red Dead Redemption is a third-person shooter where you're the gristled cowboy with a dark past who's fighting to go straight. The main story is hours and hours, the scenery reaches for miles, side quests with real stories are littered everywhere, you can collect pieces of outifts, or tame horses, or shoot horse thieves, or save damsels, or get robbed by damsels. It's a jillion things to do, and you could easily spend a month finding all the hidden bits.
Also, pardon the "gee wiz," but whoever did the lighting for it deserves a medal -- sunrise and lightning storms were my favorite. They really nailed the Western genre. The music is similarly on target, though after a few hours I turned it down so I could run Pandora on a laptop. It's a remarkably pretty game, making it good for spectators, too. Yeehaw!