The big one for me has to be Super Metroid. Before Metroid Prime came out, I wanted to play its legendary predecessor. One of my friends had also absolutely loved it growing up and was pissed when he heard MP would be 3D. Anyhow, it fucking rocked my balls off. The atmosphere, the boss battles, the powerups, the music...it was all so amazing. And it had to be about 7 years after the game originally came out and it still was awe-inspiring. That is the definition of a classic game.