Chrono Trigger was awesome, but I didn't discover it for a while and my playthrough of it was on an emulator. I guess that title belongs to the oldest game I have, as well as my first and favorite: Pokemon Yellow!

Castlevania

Champion's of Norath, for the Playstation 2. That game was my childhood on a disc, played it for hours and hours with my brothers. Barbarians, unite! XD

I'm from the generation of the Nes/Snes, so it's mostly going to be the old zelda's, mario's, metroid's etc. Streetfighter II is also very high on my list.

I could list a few I liked but the love of my gamer-life is most likely Panzer Dragoon Saga.

Legend of Zelda Ocarina of Time because it was the game that made me a Zelda fanboy and is one of the only games that I can play anytime when I'm bored and not frustrated whatsoever.

Honorable Mentions:
Super Mario World
Sonic 3 and Knuckles
Chrono Trigger

Wolfenstein 3d... maybe Daggerfall

Bubble Bobble.

Tony Hawk's pro skater 2, remember playing that on my N64 almost every day after school, great days

Atari 2600- Space Invaders

NES- Megaman 3, Crystalis, Mario 2 (Yes, Mario 2 and not 3), Castlevania 3, Dragon Quest 3, Final Fantasy 3, Sweet Home, Castlevania 3, Contra, Gargoyle's Quest 2, Ninja Gaiden

Genesis- Ristar, Strider, Sonic 3, Contra Hard Corps, Castlevania Bloodlines, Phantasy Star 4, Shining Force 2, Streets of Rage 2, Splatterhouse 3, Shinobi 3

SNES- Chrono Trigger (Best game evar), Final Fantasy 6, Megaman X, Earthbound, Clock Tower, Dragon Quest 5, Legend of Zelda Link to the Past, Demon's Crest, Killer Instinct, Super Metroid, Breath of Fire 2, Super Castlevania 4, Terranigma, Tales of Phantasia, Super Mario RPG, F-Zero, Super Bomberman

PC Engine- Castlevania X, Splatterhouse, Demon's Crash

N64- Resident Evil 2, Conker's Bad Fur Day, Ocarina of Time, Super Smash Bros, Megaman 64, Killer Instinct Gold, Bomberman 64

PS1- Resident Evil 3, Metal Gear Solid, Silent Hill, Megaman X4, Final Fantasy 9, Castlevania Symphony of the Night, Strider 2, Tekken 3, Chrono Cross, Legend of Dragoon, Xenogears, Tomba, Parasite Eve, Clock Tower 2, Crash Bandicoot 3, Spyro the Dragon, Breath of Fire 3, Dragon Quest 7, Syphon Filter

Too numerous to count. But I did enjoy playing Super Mario Land 6 Golden Coins (the game that Wario debuted in), classic Sonic The Hedgehog, Pokemon Crystal, and if I remember rightly, The Legend of Zelda: The Link To The Past.

Although I did once have many games for Playstation 2, xbox, Gamecube, Sega Megadrive II, Nintendo DS, PSP, and Gameboy Color/Advance. Unfortunate circumstances means I no longer have them. Did enjoy playing Black, GTA San Andreas, Medal of Honor, Crash Bandicoot and others.

Ah the old games how I miss them...

Super Mario
Twisted metal II World tour
Battle arena toshinden 2
Speed racer
Crash Bandicoot
Crash team racing

Oh my child hood...
snes: kirby super stars
snes: Killer Instinct
n64: Conker’s Bad Fur Day
gamecube: SSB Melee

Final Fantasy Tactics
Goldeneye:Rogue Agent
Need for Speed:Most Wanted (first)
Tomb Raider
Goldeneye 077 (n64)
Bloody Roar

The Barbie Detective carnival caper game. It was great, I loved playing that when I was younger. So much atmosphere.