Depends how far back you consider "classic" If we're including Dreamcast and Playstation then there's a few. If not then there's still a good few megadrive and SNES games that are ace and that I still play.
Pilot wings (snes)
A link to the past (snes)
streets of rage series (megadrive)
populus (master system)
A good few others too.
I would say any sort of 2D games.
Super Mario 3 in my opinion would be timeless.
Any 3D game over the years would probably lose its luster just because it would be kinda of ugly. There would be a few games like Half Life that would still be a ton of fun, but most people would say " Man, this game would be awesome remade with today's graphics."
Final Fantasy 7. Too many people call it overrated, but I feel that it's a landmark game for it's depth, characters, and graphics.
Super Mario 64. The Mushroom Kingdom has never been more alive with it's awesome 3-D graphics.
The Legend of Zelda: Ocarina of Time. Hyrule came to life with massive world gaming. Truly an emotional game.