This is an odd question, i know, but it just randomly popped into my head tonight and I thought it was interesting. You know those games that you play that just have a nice feel and atmostphere about them. The best way I can describe it is the feeling you get when you boot up your favorite game to play for the 7 millionth time, but even though you have played it over and over, it is still just as fun to play this 7 millionth time as it was the first.
For me, this game has got to be Super Mario Bros. 3 (i know, generic). It's not even the nostalgia of my childhood, though. The entire game just leaks a special atmospheric quality that I have found in very few games since that (a few of the original megaman titles and NSMB Wii have got this for me)
What about you?