For my early childhood, Super Mario All-Stars + Super Mario World and Tetris and Dr. Mario are what resonates with me the most. These were the first video games I played and I still love them to bits even today. I have so many memories from just...weird things in these games, haha. Mainly making up words to the music and other things like that. :P I'm not very good at Mario games, but I always make time to sit down and play All-Stars when I go to my grandmother's. I should also mention that it was her that introduced me to video games. <3
For my later childhood, my most nostalgic games are Kirby 64: The Crystal Shards, Pokemon Stadium 2, and Pokemon Sapphire. Kirby 64 was the first game I beat, Stadium 2 was always a blast to play with my best friend, and Sapphire was the first main series Pokemon game that I beat.
For my all my teen years, my most nostalgic games are The Legend of Zelda: Twilight Princess and Ocarina of Time, Pokemon Black and White, and Kingdom Hearts II. Twilight Princess was my first uhhh...how do I phrase it? It was my first time to be hyped for a Zelda game since becoming a fan after playing Wind Waker. I remember reading all the Nintendo Power articles about it...gahhh. Memories. :( Pokemon Black and White came at a hard time in my life and the week it came out here in North America, it allowed me to escape from my troubles for a few days as I blazed through the game and continued to help me in months to come. As for OoT and KH2, I played these years after they had been out, both in my senior year of high school, and I was totally obsessed. So while I didn't go out and do all the cool high school senior things, I did play the hell out of those games and they're some of my favorites in their respective series.
As for my current early adulthood, Chrono Trigger is super nostalgic for me despite only playing it about a year ago. I don't know why, it just really feels like I've played it more than that one time so it already has that timeless feeling with me. I'm sure that Tales of Xillia is going to be something that's nostalgic for this time in my life as well once some time has passed since my initial playthrough. Ughhhhhh I love that game...