My brother had gotten CD1 from a friend, either because he had gotten two CD1's and didn't realize there were 3 CDs in total, or something like that.
Anyway, I had CD1 for years. I didn't really dare play it, because I thought the reactor part was scary (I was really not old at this point), and I'd jump every time a battle would start. I think I had only ever played up to the first boss.
Then, one day, me and my friend were looking for something to play, and he said "why don't we play that!" I went "I don't know, it's kind of scary". Needless to say, we started playing it, and we really put a lot of time into it. My fondest memory is probably finishing CD1, all "NOOOOOOO" and then it says "insert disc 2" and it goes something like this:
"WHERE'S DISC 2?"
"I DON'T HAVE IT, I ONLY EVER HAD 1"
"ARE YOU SURE??"
"YEEES"
"FUUUU"
and we ran out and bought it right there and then, because we just HAD to continue.