I've been playing it since the first one back in the 80's and it's always been my favorite Nintendo franchise. Aside from the stellar gameplay, the reason why it had such an impact on me is the atmospheric music and sound. Take the first game for instance. Even though it's an 8-bit game, as soon as that now-iconic theme kicks in, you truly get a feeling of dread and isolation. You feel like you're on another planet and one that is quite hostile.
People don't really think of music as being as important as it is but a great sound track can be the difference between a good experience and a great one.