I'm pretty nostalgic for lots of games right up until PS2 generation and have revisited plenty of them I could probably list 50 games or so easily but in order to control myself I'll chose some restrictions. First I'd say Sonic the Hedgehog on Mega Drive is number one in terms of the game with the most great memories attached to it, but in terms of games that evoke immense nostalgia that I haven't played since the time period I originally played them and so they only really live on by the sheer power of nostalgia,

-Rainbow Islands (Amiga)
-Super Pipeline (C64)
-Blinky's Scary School (C64) Playing Mystik Belle reminds me of this game and once I discovered it and saw Way Forward was attached to it I bought it on the basis of nostalgia for this old C64 game
-Socrates (a VTech edutainment console with separate cartridges, the boot up music in particular makes me feel nostalgic)
-Barcode Battler, I still own several NES games and probably a few other games missing a barcode from their boxes due to this system that I credit with starting my love of RPGs (my joint favourite genre) and I distinctly remember when I first played a proper turn based RPG I thought "this is kinda like barcode battler, cool"
-Multiple Dizzy games on C64

I wouldn't say any of these are remotely close to being my favourite game but I have a serious soft spot for any of them no matter how bad they may be. These are also some of the earliest games I played and still remember.