1. Gears Of War. I just can't get enough of it and the chainsaw.

2. The Legend Of Zelda: Ocarina Of Time. Only one word can describe this game... masterpiece.

3. The Elder Scrolls IV: Oblivion. I played this game to death.

Ocarina of Time/OoT:Master Quest. Self-expanatory.

Honorable mention: Tetris (of any sort, but the DS version is particularly excellent), Mario Kart DS, Half-Life 2, Zelda: Phantom Hourglass, Zelda: A Link to the Past, Super Mario 64, Goldeneye 007.

Ill go with FF6.

Its just the combination of getting that game for christmas / how awesome the game was.

Man that was an awesome Xmas..My younger brother and I opened it up and seen this cool looking, white, creature on the front with a purple back ground.
Boy we didnt know what to expect!!OH BOY THE NOSTALGIA Great times :)

crash bandicoot (naughty dog era)
spyro (insoniac era) both from when i was younger loved them yo the max

It is too hard to pick one. Here are my top ones:

The legend of Zelda: Ocarina of Time- This game was just amazing. The gameplay, bosses, story, cut scenes, ending, everything was just perfect. At first I didn't like it, but when I finally got through the whole thing, I just fell in love with The Legend of Zelda.

Super Mario 64- My first game that made me into the gamer that I am today. The gameplay is what made this game awesome. Also the music and creative worlds helped it achieve greatness.

Super Mario Bros. 3- Pure 2D greatness. Great music, gameplay, challenging levels, easy controls, tons of powerups... this game has it all. It is still great to this day.

 Edit: if I HAVE to pick one, it would probably be Ocarina of Time.

The greatest game off all time i would have to say is The Legend of Zelda, The Ocarina of Time. The reason was at the time i had never played a game as much. I was never into games at all really. After playing this game i wanted more. I wanted alot more. Ocarina of time had it all for its time. great story, great graphics, great gameplay, amazing mini games, fishing, this game had it all. I have never played anything as good since Ocarina of Time came out. I believe i will never play anything as good since.

Either:

Gran Turismo 2 - I logged a lot of hours playing that one
Crash Bandicoot 2 - Amazing game, only for PSone
or
I would acually have to put down Call of Duty 4. Its the best one in the series.

@twesterm
How can you say FF6's gameplay was bad, unless you really hate Active Time Battle? I love that game, for all the reasons you listed AND its gameplay.

Tomb Raider 1 and the following describes exactly how I feel about that game and what has become of the series:

http://www.consoleob.com/trapsp.html

Words by Edwin Evans-Thirlwell

Tomb Raider ain't all about the boobs. You know this, I know this, any gamer worth his salt knows this. Ignore the pixellated buttocks and painfully tight shorts- Tomb Raider is about those breathless few seconds as you leap into the dark air, praying that the ledge you stretch out your fingers for isn't just a seam in the rock face, or the rush of wonder as you crawl out of a tunnel to discover a vast, crumbling and long-forgotten city. Tomb Raider is about awe, loneliness, determination, sanctity and giant rolling boulders

Sadly, this is not the Tomb Raider memorialised in the popular imagination. Over the course of her eleven iterations, two movies and nine real-life representatives, boobs (with their action movie adjuncts guns, explosions, fast driving and sleazy banter) have come to the fore, obscuring both Lara's taciturn, hard-as-nails persona and the truly unprecedented experience of which she was the centre.

Now only the most puritanical of apologists would deny that Lara's status as the first mainstream videogame sex symbol has played its part in her success, and you can't help but feel just a teensy bit cynical when Toby Gard, her disenfranchised creator, starts to whinge about her BMI-defying attributes. If you wanted to put personality before looks, Toby, why didn't you give Lara a fifty-inch waistline and a yashmak?

But let’s get our priorities in order. Tomb Raider was a landmark game because it demonstrated, along with Super Mario 64, the cavernous possibilities of three-dimensional gaming, not because of the cavernous nature of Lara's cleavage. It was also fantastic because beneath all the HIGH OCTANE THRILLS and tedious, trivial gunplay, it was a game which expressed, with a poignancy matched only by its greatest descendant Ico, the fragility of a human being lost in an ancient, hostile landscape. Lara's very obvious femininity has a subtler role here, inspiring feelings of protectiveness and empowerment among male and female players respectively.

And thankfully, this is the Tomb Raider Crystal Dynamics remembers. Even given the relative limitations of the PSP hardware, Tomb Raider: Anniversary is a masterpiece which simultaneously advances the Legends formula and recaptures something of the spirit of the magnificent original.

The legend of Zelda: Ocarina of Time....I don't even know how I wanted this game, all I can remember is I really wanted to play it (I was 11 years old I think) And wen I got it... WOW, I was stuck in kokiri forest for a week and I don't really care, I didn't understand almost anything of the text (I didn't know english when I was 11) and I don't really care because It was so amazing to run, to cut, to play, to ride, to find....
Yeah, that was my best experience with a videogame....