SO many special moments, but ... SPOILERS WARNING.
MGS 3, the ending was too intense for me when you discover the truth about The Boss. I literally cried.
Most of the N64 games were a great introduction for the 3D world. With SNES is where I started my very first touch with the videogaming world, concretely thanks to Stunt Race FX.
And the GBA, I guess played a great deal of wonderful games. PS2 too, but not so many: Rayman titles, GTA San Andreas, Woody Woodpecker, etc.
Some Gamecube titles such Super Smash Bros. Melee, Zelda WW, Mario Sunshine, Donkey Kong Jungle Beat.
Wii games like Metroid Prime Trilogy, Mario Galaxy, Zelda Twilight Princess, and few more I guess. Nintendo DS? Many of course! Zelda PH and SP, Super Mario 64
Undertale affected me the way to see games overall as well.
Gaming is a wonder of experience because of the many ways can let you interact with a fictional world, and the feelings they can transmit because of the power of the narrative. Combine both things and you'll get a supreme infinite of possibilities to experiment, left with a lot of creativity that you could create in your own.