Back when I was a kid, my mom rented me Metroid on NES. Back then, there was no internet, and I had no friends who owned the game. So literally, it was just me and the game. No instruction manual. No explanation. No idea of where to go or what to do. All of this made the intended (on Nintendo's part) impact of being stranded alone on Zebes that much more than profound. I had no skills. Everything was brand new. I was alone in this dangerous world with this foreboding score--and it freaked me out. Needless to say the game kicked my hindquarters and ate my lunch... but it's still something that I look back on fondly.
I don't know about anyone else, but when I hear the original's opening score, it still sounds ominous as hell.