Super Mario 64 and Paper Mario.

Paper Mario, Super Mario 64, Mario Kart 64, Mario Party 2, Crash Bandicoot 2, Sonic Adventure 1 and 2, Mario Party 4, Super Mario Bros. 3, Kingdom Hearts 2. etc. I'm pretty sure that there's more, but I don't really remember them. And, yes, I was a HUGE Mario fanboy growing up.

The more love Paper Mario gets the happier I am.

If I had to pick one, it would be Super Mario 64. That castle music is a blow to the nostalgia bone every time.

Mostly PC games like Age of Empires, Warcraft 3, The Sims, Counter-Strike, RollerCoaster Tycoon, Zoo Tycoon, etc.,
but also SNES and N64 games like Megaman X, Goldeneye, Donkey Kong Country, Diddy Kong Racing, etc.

I find it more difficult to feel nostalgic for games I have played recently, even if I primarily played them a long time ago. It's a bit saddening to replay old games because I know I'm systematically destroying my nostalgia by replacing old memories with new ones.

Strangely, I already feel an immense rush of nostalgia when listening to the Colony 9 music from Xenoblade.

I think the most nostalgic game I could play nowadays would be Pokemon Blue. Haven't touched it in forever.

8 and 16 bit era

Mario, Sonic, Zelda, Metroid, etc. That era always takes me back to childhood.

Just the beginning scene from ratchet and clank 1.

Goldeneye, F-Zero X

Crash Bandicoot 3, Crash Team Racing, Crash Bash, Crash: The Wrath of Cortex, Rayman 2: The Great Escape, Ratchet & Clank 3, Hogs of War, Tekken 3, MediEvil... And so many other Playstation classics. :D