I remember playing a black and white platformer, like Streets of Rage, where you beat up werewolves, at an Apple computer store, must have been an early Macintosh, that was the first game I ever played, needless to say I was very amazed.
I only got a PC in '95 and, while I played the shit out of games like Doom, Heretic, ROTT and Duke 3D, graphics like that were pretty much the norm so they never wowed me much. A couple of years later, I got my first Pentium, and that's when I was completely astounded by the giant leap in quality, games like POD and Blade Runner, but none impressed me more than Quake, there was no possible comparison to any other fps, added to the fact it was the first game I played online deathmatch, it's still my favourite game of all time.
Soon after, Unreal came out, and I was completely blown out of water once again, actually twice, the first time playing it and playing it after getting a Voodoo2, it was that big of a difference. It also came with Incoming, which had some remarkable explosion effects, that, Unreal and Turok were the first 3D-accelerated graphics I'd seen.
The last time I was wowed by a game wasn't even by a finished product, it was by the leaked Doom 3 alpha. When I got it first, I still had a GeForce2 MX so, for all its beauty, running at 1fps or less, it just looked like a slideshow. A few months later, I managed to get an Ati 9800 Pro, and the D3 alpha was one of the first things I tried on it, running at 20 to 40fps it had the most beautiful graphics I'd seen, approaching pre-rendered quality, shooting a hanging ceiling light and watching the shadows dance around was just amazing and unheard of.
Since then, there haven't been qualitative leaps large enough to wow me, Far Cry and Crysis were probably the closest, but even those weren't enough of a departure from the norm to amaze as much.
