PC Another Lifeless Planet (and me with no beer) was fantastic for a text adventure. Testdrive pushed graphics hard Wolfenstein 3D was incredible at the time being surpassed by Doom then Quake. Day of the Tentacle for its high quality cartoon animation opening sequence. Unreal on a Voodoo graphics card was something else. HL2 of course with its physics (ragdoll) engine and jump in polygons. Doom 3 for its advance in polygon count again.
NES Super Mario 3 was a leap believe it or not. Blew people away back then. Battletoads had huge sprites which wasn’t a NES thing until they did it.
SNES Fzero and Mode-7 graphics Donkey Kong Country, its CG was nuts at the time FFVI’s snowfield theatrics Starfox
Sega Earthworm Jim had a great art style and pushed edgy games Another World/Out of this World for that opening and style was amazing and still holds up!
N64 Super Mario 64 Japanese demo at Babbages in a mall before the US demos came out. That was mind blowingly smooth. Waverace 64 for its water effects. Ocarina of Time for its cinematic 3D story telling and fun gameplay.
Neogeo Metal Slug was incredible in the arcade for all the sprites moving on screen and action. So much fun still to this day.
PlayStation Resident Evil was incredible for the atmosphere. Tomb Raider for more detailed 3D environments. Warhawk also stood out for its great use of the analog dual joysticks. FFVII for its cinematic story telling and FMVs. Wipeout for its fast paced racing and great OST. Grand Turismo for its photo realism simulation and physics.
Dreamcast
Seeing the demo of Sonic Adventure blew my mind since it was so fast and colorful. The whale jumping after Sonic as you raced away was burned into my brain.
Gamecube Wind Waker, still love that art style and loved the exploration that was enabled by sailing the sea. Didn’t feel that again till BoTW.
Wii Super Mario Galaxy for its outstanding OST and gameplay.
Playstation 2 Grand Turismo 3 Little Big Planet had incredible art direction and unique play style
Wii U/Switch Breath of the Wild. What an intro to a new world! They absolutely pushed the hardware to the limits on the Wii U.