I think it might have been 94 or 95 when I was in middle school, a friend down the street showed me Doom for the first time. After that, I was a total PC Gamer.
Began totally obsessed with anything based on the Doom engine. Doom, Heretic, Hexen, even Strife. My friend actually tried to get me interested in Wing Commander, the Gold Box games and a smattering of less flashy tactical or simulation games. But I pretty much felt like Doom and it's ilk were video games, and branched out relatively little. The radius of my interest expanded to cover RTS after I discovered demos for Warcraft and Command & Conquer too though. That's when Blizzard and Westwood popped onto my radar. Eventually Diablo and Diablo II came along through that exposure. My relationship with Westwood was less fruitful outside of Command & Conquer.
I was insanely excited for Quake, and ran around the empty halls of QTest obsessively. I only ever got the shareware version of it though. And never played GLQuake either. It wasn't until Quake 2 came out that I had a card with a 3d accelerator. A Riva 128. In a P120. And I remember it was a Shuttle HOT-555 motherboard too.
It was the first computer that was all mine. A smattering of hand me down parts and budget items. My father built it with me, doing most of the work, Christmas morning. He showed me how to connect the AT power supply to the motherboard. A bit of knowledge immediately rendered obsolete by the ATX standard. I've never plugged in an AT power supply since.
My friend did succeed in planting the seed of having an interest in RPGs. And despite losing touch with him, when CGW gave Might & Magic VI downright radiant reviews I played it and totally fell in love with it. And I eventually played and loved Wing Commander: Prophecy as well. Early in highschool I was obsessing over Fallout, Baldur's Gate, Planescape: Torment and the like coming out of Interplay.
By the back half of highschool it was all LAN parties and Quake 3, later supplanted by Counter-Strike 1.6 which I enjoyed far less. Those two games, and a bajillion mods we'd just try out when we were bored. Action Quake, Science & Industry, others far more forgettable. Some games we'd be super excited about, and pirate off IRC channels, only to play a single evening. Like the night we were all racing to pirate Freedom Force and make immature gimmicky heroes. We laughed late into the morning, and then never picked the game up again.
When I interned in college, I finally had enough money for a real, few compromises gaming machine. I built myself an Athlon 64, Geforce 6800 GT system just to run Doom 3 as well as my money could run it. That machine also took me through Half-Life 2. I dabbled in Prey and Farcry, but they made much less of an impression. This is also when I got into overclocking, and I eventually burned out the machine. Unless someone threw it out, it's still sitting in my parent's basement. A part of me is tempted to try to scavenge it for parts, see if anything is salvageable. But that would involve actually speaking to my mother, and that's just not going to happen.
I gotta admit, I donno if it's just getting older, or games not being as good, but very little has made the impact on me those games did. Maybe when I discovered Minecraft during it's alpha or beta around 2009 or so?
Win95/DOS 7.1 - P233 MMX (@2.5 x 100 FSB), Diamond Viper V330 AGP, SB16 CT2800
Win98 - K6-2+ 500, GF2 MX, SB AWE 64 CT4500, SBLive CT4780
Win98 - Pentium III 1000, GF2 GTS, SBLive CT4760
WinXP - Athlon 64 3200+, GF 7800 GS, Audigy 2 ZS