Fallout 3

Definitely one of the most original, in-depth, all around games I would say created up to this point.  This is obviously a very swayed opinion because this is by far one of my favorite games in console history.  Fallout 3 combines multiple genres into one, fantastically!  Technically people will say it is an RPG, and it is, you are thrown into an unfamiliar world, into an intriguing storyline, and into a character.  I haven't played very many RPG's in my video game history, so I don't really know the common attributes of them, however, but Fallout has the whole deal.  Upgradeable skills, great "perks", and a leveling system with experience.  Beyond just a role-playing game though, Fallout 3 also combines aspects of an action-shooter, adventure, and problem-solving game with great finesse.  The game is immersive and unbelievably realistic, giving you the choice to do ultimately whatever you want.  Steal ruthlessly, kill whomever (main characters included), go wherever you want, skip missions, lie to people, and even charm your way through some situations.  Apart from the actual gameplay, the game itself, is incredibly "FULL."  There is a main plot, however, seemingly everyone you talk to will have some task or side mission that they want you to do.  This fact coupled with the immense size of the map, make the game playable for more than "a couple hours," like many games today.  Having completed only half the game I have prolly spent 40 hours of pure gameplay already.  AND, the game has great replay value, since you can approach the game with different skill sets and choices each time you would play it.  You could be a sneaky evil thief (like myself), or the strong, blunt force hero.  Oh ya, I forget to mention, insane gore...  I have to look up how many hours were put into making it because I can't imagine how long it took to put every plate, tin can, pack of cigarettes, etc., that exists in the game, in it.