For me, it was back in early 1997. My best mate back then (still is to this day) had purchased a new game from his local newsagent. Looking at the CD, I remember how cool it looked, and how the word "Diablo" made me think "Wow, this'll be awesome."
I remember the nights fondly. How I'd take turns leveling my lowly Barb with my mate and his brother, and they leveled their characters. We had this pact of sorts - every time we leveled, it was the next person's turn. They had a level 15 and level 20 Barb; I had a level 1 when we started. As you can imagine, I didn't get much play time.
But, I was hooked.
When it became available, I purchased Diablo for the Playstation (PSX). I was surprised at how smooth the port was. Add to that, you could plug another controller in and could do split screen MP. Made for many a sleepless night.
Fast forward to the year 2000. Diablo II is almost released. I remember mentioning to a sparring buddy at karate that I think there would be a Diablo III eventually - he said "No, they'll tie it all up with this and the expansion pack, and D2 will never die." He was half right.
I started with a Paladin. Loved it. Except, when it was first released, there was no cap on the amount of hits you could do with Zeal until you hit the max, whatever it was, and you kept going until you were finished. Now, imagine if your hit rate sucked? Yeah, that was me. Still, it was fun.
I ruined D2 for myself. I'll admit it - I eventually used a trainer/editor. Mostly, this was to bypass Act 3. I found it so boring. That, and the fetishes...urgh. After that, was LoD, and well, I still play it occasionally to this day.
So, now on the eve of D3, I'm excited, if only to see how they explain Diablo coming back with the soulstones being shattered, etc etc etc.
Oh, and I finally get to get past level 13.
TL;DR - How did your being a Diablo fan start ?