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.
People shit on this stuff like it's terrible garbage that no one would want to play, but I remember playing Zelda on my friend's CD-I and being blown away by a video game having fluid animation and voice work. Up till then, I had only experienced NES games, and a few super Nintendo ones. But that shit was amazing to me. The IR remote control, on the other hand, wasn't.
Then there's was also virtual boy. I remember trying it out at a Sears and thinking how cool it was.
Those qualities were really impressive back then. I remember being super impressed when games started having cut-scenes.