What makes them your favorite games?

[The_Liquid_Laser]

I got the idea for this thread after reflecting on our annual top 50 games list.

Think about your top 3 favorite games.  What is it about them that makes them your favorite games?  Is it pure nostalgia, or do you keep playing them even after becoming an adult?  You might have even discovered some of these games as an adult.  Often times, there is something unique or especially well done in the game that keeps you coming back to it.  Maybe you just want to revisit that game's world or characters.  Maybe it has unique game mechanics.  Maybe you feel the whole experience is just incredibly well polished from top to bottom.  It may be something else entirely that I haven't suggested.

So, please give your top 3 favorite games of all time.  Then tell what it is about each game that really makes it stand out above all of the other games out there.