I can only reply to this thread with one comment:
"So many games, so little time!!!"
During the last year or two I rarely played games on release... then there's the bunch of games I've been meaning to play since forever. It makes me sad.
If I must contribute a title however, I played Portal about 12 months after its release when I started wondering how a physics puzzle game could win so many awards and get so many good scores. I found out the good way!
EDIT: I also remembered that it took me ages to finally play Warcraft III + Frozen Throne