I remember a few from various stages of my life (born 1984).
Seeing the demo footage of Sonic 2 in Woolworths and thinking the leaves falling down in Aquatic Ruin zone was so cool and advanced.
The original Sega arcade of Virtua Racing with the moving cars completely blew me away.
I remember my uncle loading up Cannon Fodder on his Amiga, and a REAL song with REAL music came out, along with REAL photos. I was amazed haha.
A few years on I remember a PlayStation demo disc having promo footage of the first Gran Turismo and it looked so real to me, I watched it over and over. The first Driver on PS1 looked absolutely amazing to me also.
I remember being in like a GameStop or whatever the store was prior to that in my area. The tvs in the store were playing a teaser for the new Zelda game that was going to be coming out. I think this might have been like very early concept of windwaker before they went with the cartoon cell shaded style. I remember there was a sword fight between I think Link and Ganon. I remember thinking that games had peaked at that point. Of course we didn’t end up getting exactly that, but the memory remains.